I'd dispute that statement, Stella was quite strong 4.8-5.2 less than Fullers ESB 5.5, Bishop's finger 5.4 both freely available behind the bar. At the same time as Stella and still available.
Stella's USP was its quality and cost (remember the 'Reassuringly Expensive ads?) Come the millennium and Interbrew becomes Interbev and starts cost cutting, the Barley is cut with cheaper Maize and the ABV reduced. The embossed cans are likewise replaced with printed cans.
So less the UK couldn't handle the high ABV, albeit one lower than some premium national beers more that the accountants got their sticky fingers on the product. The effect was that from double digit growth in the 90s it went into a similar decline at the turn of the century and picked up the 'wife beater' label on the way.
The 5%+ abv beers sold many years ago were standard fare, with some lighter ales sold as table beer.
Some mild ales were 6% and more. WW1 came along, Lloyd George and his Methodist instincts persuaded the government that rampant beer-drinking could destroy the war effort and pub hours were shut, beer duty increased and cuts made in the strength. Brewers didn’t care that much, they made the twice the ale with the same malt.
The government even took over the pubs of Carlisle as they were close to munitions factories.
Even now, brewers in Britain can still sell an “IPA” at 3.6%. Which is a rip-off. Tell the punter what it is. Lightweight slurping beer.
And Stella? Crap beer with a huge marketing campaign, like the rest. It never was quality, it just got sold better, colder and in fancier glasses.It has a high quantity of corn/maize starch in the brew which is cheap. Accountants love it due to the profit margin.