As Bill D noted, today`s AutoGlass is different stuff from what it used to be.
Eh, I dunno...I`m on-board with the idea that "what works, works, no need to guild the lilly by using something fancy if it`s not necessary" and I just hit my glass with abrasives made for paint.
But OTOH, I knee-jerk against "improvised solutions" to stuff, at least when there are products specifically designed to do the job properly. IPA + Lava just doesn`t sound as likely to work optimally as a Glass Product developed by a major manufacturer of such stuff. "Hey, we don`t need some laboratory or stringent QC/Testing Protocols and neither do you! Just grab your Rubbing Alcohol and a bar of Lava.." Nah, not me thank you.