Also, many people from older generations were discouraged from experimenting with sex before marriage, so might have assumed they were straight as homosexuality was seen as deviant. I don't remember anyone being out as gay at my school (large mixed-sex comprehensive) in the 70s. Not anyone, which means that a lot of it must have been either hidden, suppressed or just not realised. Maybe people came out later, maybe they hid it, or maybe they just settled for a more comfortable and mainstream life - who knows.
I think it's a good thing that young people can be who they want to be, but really wish adults would leave them to it and not try to influence them.
I very much doubt that 1 in 4 people are actually gay - it's much more likely that that number has experimented and may have ticked the 'bi' box. Either way, I have no idea why any adult would think it was 'wonderful' or think anything about other people's sexuality really. There should be no value judgement put on sexuality - it is just what it is, and young people shouldn't feel that one way is 'wonderful' and, by definition, another is less so.
Also, in the 'Boomers'' day, there was no 'TQ+'. If you add in all the options Stonewall have shoehorned into the LGB category - many of which have nothing to do with sexuality but are about 'identification', then of course the numbers are going to be higher.