There are tons of reasons why live rock and roll is in its final death throes. Youtube is a huge part of it, but there are other reasons, too:
1. It's no longer fresh.
2. Tinder. Bands used to get their start playing at bars. Bars are drying up. Young people rarely go to bars anymore because they don't have any incentive to do so. Between hookup apps and cops cracking down on drunks, there are a lot fewer places for shitty rock bands to play.
3. Streaming. Making your own CDs or, before that, tapes, used to be a cumbersome process of setting up dad's garage or mom's basement as a shitty makeshift recording studio. You'd make your recording over a weekend or two, burn or dub physical media, then sell it for $10 to a handful of dedicated fans. Now, you can download an entire band, grab a microphone, and record all you want by yourself and stream it for .004 cents. For one, you don't NEED your buddies to lug their drums and amps over and for two, even if you wanted to approach it that way, it wouldn't be worth the hassle.
4. Culture. We've shifted culture away from things that take patience to learn. Video games used to be painfully difficult, but now they all start with a tutorial and you can always start from your last save if you mess up. In the USA, it's nearly impossible to get a car that's not automatic. Homecooked meals come in kits now. Everything is made easier, which is great, but it means that life goes at a faster pace, so there isn't time to go deep with stuff anymore. Even learning to play an instrument these days is more of a solo thing. You take lessons online, which increases the barrier of just jamming with other people, which leads to fewer bands.
It still sounded 90% the same as post-Back in Black AC/DC, though.
