The Brian Jonestown Massacre arrive in the UK just before the documentary that effectively made them famous, Dig!, returns to cinemas: a “reimagined 20th anniversary edition”, which brings the story of the rivalry between the band and their frenemies the Dandy Warhols up to date. On release, you would have watched certain who came out on top. The Dandy Warhols had recently been catapulted to success after a Vodafone advert transformed their single Bohemian Like You from a flop into a global hit. The Brian Jonestown Massacre, meanwhile, had ended the doc in a state of disarray: drug-damaged, dropped by their label and thumping each other in the middle of a gig.

Two decades on, the outcome is less clear. The Dandy Warhols’ moment in the spotlight proved fleeting, while the Brian Jonestown Massacre have a cult following big enough to warrant the publication of an acclaimed memoir by percussionist Joel Gion and big enough that this large UK tour includes a date at Brixton Academy. Perhaps some of their audience is drawn in by the band’s myth – big on excess, volatility and danger – in which case, they’re in for a disappointment tonight. The gig’s a little shambolic – songs occasionally take a couple of goes to get started – but the only sense of danger is that someone might slowly die of old age while the band are silently retuning their guitars between songs. Long-haired, wearing Bob Dylan’s hat from the cover of Desire and directing proceedings from the side of the stage, Anton Newcombe cuts a rather inscrutable, aloof figure: if there is a visual focus, it’s Gion, tapping his tambourine.

One suspects most people here have bought into the idea that Newcombe is an errant underground genius. Certainly, he’s a man with a stock in trade, as evidenced by the ease with which the set ranges across the band’s 20-album career, eliding songs from the mid-90s – Vacuum Boots, That Girl Suicide – into tracks from their most recent album, The Future Is Your Past. Regardless of their vintage, they all seem of a piece, mining a sound that, like a lot of their album titles (Who Killed Sgt Pepper?, …And This Is Our Music), is made up of reference points: the kind of riffs purveyed by the garage and psych bands on Nuggets and Pebbles compilations, the metallic jangle of the mid-60s Byrds, the blur of shoegazing and the psychedelic drone of Loop and Spacemen 3.

As they launch into Pish or Forgotten Graves, you’re aware that Newcombe is really adept at coming up with melodies and guitar figures that sound immediately familiar, as if you know them already from a song you can’t quite place – a genuine skill – and that the music that surrounds them is a lot like old-fashioned, ungentrified indie, from an era before Britpop made alt-rock a mainstream concern. And that, one suspects, is part of the appeal. Certainly, the audience in Bexhill are largely old enough to warmly recall a time when bands that sounded at least a bit like this were the backbone of John Peel’s Festive 50: how distant it all seems in the 2020s, when a lot of what gets called “indie” sounds remarkably like the glossy 80s pop-rock you were listening to John Peel to avoid.

There really isn’t much music around like this now, which gives the Brian Jonestown Massacre a weird USP. But unique or not, there are issues tonight. You would expect a band with four guitarists to feel overwhelming, but they somehow don’t. For all the manpower on stage, there’s a trebly thinness to the sound. Plenty of their songs devolve into drone-heavy instrumental passages, but they never quite envelop or hypnotise you. It’s not helped by the fact that almost everything they play proceeds at the same mid-tempo pace, powered by tumbling, Tomorrow Never Knows-y drums: despite the longueurs between songs, it all starts to blur into a wash, one long rummage through rock’s history books. Anemone stands out by dint of its familiarity – it’s by far their best-known song.

It is, to borrow the phrase Newton uses to describe Bexhill in January, perfectly pleasant, and it’s hard not to be impressed by the Brian Jonestown Massacre’s longevity against the odds. But it’s equally hard not to think a massacre should be a little more bloody than this.

• The Brian Jonestown Massacre play Rock City, Nottingham, 4 Feb; then tour the UK and Ireland until 20 Feb.