Mumford & Sons are the band that launched a thousand banjos. The little British folk foursome sold so many records and won so many Grammys while wearing old-timey vests and playing traditional American music that everybody eventually decided that they had enough already with all the manically strumming guitars and foot-stomping singalongs.

The everybody in question would seem to include the band, which is led by singer, guitarist, and sometime drummer Marcus Mumford. His band headlined the Wells Fargo Center in South Philadelphia on Friday night in the first show of a U.S. tour for a brand-new album, Delta.

After breaking through with their 2009 debut, Sigh No More, with hit single “Little Lion Man,” the Mumfords got huger still with 2012’s Grammy-sweeping Babel, which seemed to spawn scads of mini-Mumford muppets in acoustic-rock bands like the Lumineers and the Lone Bellow.

But since then, the Mumfords have made two albums 2015’s Wilder Mind and now Delta that have taken great pains to move on and emphasize rock instead of folk or country, brooding over electric guitars and dark keyboards rather than kicking up an acoustic storm. They’ve really always been a rock band, they tell interviewers, and that Hootenanny thing is only one part of what they do.

Neither album has been greeted kindly by critics. Pitchfork made the band the target of a gleeful takedown with a 2.0 (out of 10) Wilder Mind review. Delta is an improvement, but Rolling Stone still got the knives out for it, calling it an “epic bummer.” Mumford & Sons are the band that everybody loves to hate.

Everybody, that is, except legions of fans. Delta is uneven and too long and uncertainly leans toward Coldplay and U2 in aiming for what an arena rock band should sound like, but it’s currently No. 1 atop the Billboard charts, just as Wilder Mind and Babel were before it.

Marcus Mumford sings during opening night of the U.S. tour for British folk rock band Mumford & Sons at the Wells Fargo Center, Friday, December 7, 2018. STEVEN M. FALK / Staff Photographer
Steven M. Falk
Marcus Mumford sings during opening night of the U.S. tour for British folk rock band Mumford & Sons at the Wells Fargo Center, Friday, December 7, 2018. STEVEN M. FALK / Staff Photographer

At a time when youngish acts — the Mumfords are all in their early 30s — that aren’t pure pop or hip-hop struggle to half-fill rooms the size of the Wells Fargo Center, date night with the Mumfords was sold out with a rowdy, ready-to-sing-along crowd that was more than half female, judging by the staggering length of the ladies' room lines.

The evening began with Maggie Rogers, the 24-year-old singer-songwriter whom Pharrell Williams swooned over while he was teaching a masterclass at New York University, where Rogers was a student in 2016. As she swirled around in a fringed blouse like a next-gen Stevie Nicks, her set peaked with her folktronic “Alaska,” and she later joined the headliners for Sigh No More’s tender “Awake My Soul.”

The show was hyped as being in-the-round but was really in-the-middle, with the core four Mumfords and auxiliary players on fiddle and trombone coming out on a stage that stretched across the center of the arena along the axis of the red line in hockey. Platforms rose on either side, each with a drum kit at the ready, so band members could get close to the crowd.

Two double-sided video screens fanned out like butterfly wings on either side of the room. The desired approximation of intimacy was effectively pulled off, particularly on “Timshel,” when Marcus and the other Mumfords — keyboard player Ben Lovett, banjoist Winston Marshall, and bass player Ted Dwane — harmonized around one microphone.

And how were the songs? Not so terrible, Mumford-haters. The audience loves the early stuff the most, as audiences tend to do, and in this instance, the instincts are correct. Rousing thumpers like Babel’s “I Will Wait” and “Lover of the Light” were clear highlights, earnest shouted-out declarations of devotion that set the room aglow.

But the six songs from the new album also went over perfectly well, including the particularly effective opener, “Guiding Light.” (There’s a lot of “light,” in Mumford’s songs, which are frequently illuminated with spiritual overtones. Early on in “Believe,” the band got the crowd to glow up the room with smartphone flashlights.)

Some of the new tunes are lumbering, like the leaden and repetitive “If I Say.” The band has a proclivity for literary allusion: Sigh No More’s title comes from Shakespeare’s Much Ado About Nothing; “Timshel” nods to Steinbeck’s East of Eden.

I’ve never found that to be intrusively pretentious, but it gets out of control with the new album’s “Darkness Visible,” which on Friday included a video-screen recitation by songwriter Gill Landry from John Milton’s 17th-century poem Paradise Lost punctuated by flame-throwing pyrotechnics.

That heavy-handed outburst was uncharacteristic of the evening as a whole. Mumford himself came across as genuinely humble and personable on stage, and pleased to be back out on the road in the U.S., where the band was set to play Saturday Night Live the following evening.

The show didn’t really point to a resolution to the Mumford dilemma: how to satisfyingly move forward from their folkie beginnings and sustain themselves as an arena rock band that can be authentic to itself rather than borrow from other big British bands that do it better. But the reception they received Friday made it clear that their audience is perfectly happy to stick with them as they try to figure it out.