I'm aware that many people do it and I'm aware of the reasons that some of them get away with it.
The problem is that a very knowledgeable reloader posts a long explanation of how you can shoot lead in Glock barrels and most of the people reading the post only get the part that says "you can shoot lead in Glock barrels".
Yes, if you're assiduous about cleaning, religious (anal if you prefer) about checking for leading and checking for bullet material buildup at the chamber mouth, if you stick with hard enough bullets of the proper size for the bore, never shoot jacketed bullets after lead bullets before cleaning carefully, are very careful about OAL and setback with the 180gr .40S&W loads, etc., etc., you can shoot lead reloads in Glock barrels and you'll probably have no problems.
I'm also aware that many people do it and don't get away with it, and that many people who THINK they're taking sufficient precautions really aren't. For example, I recall reading a post about a person who shot 50 rounds of lead bullet ammo through his Glock 9mm, and then blew it up by firing a single jacketed round down the leaded bore. Obviously the "check it every 100 rounds" recommendation wouldn't have helped this guy.
I don't have any problem with people shooting lead bullet reloads in Glock pistols (it's their prerogative and there's nothing I can do about it anyway). On the other hand, I think it's very important that people understand that there are a number of issues with reloading lead bullet ammunition for Glocks that don't necessarily apply to other pistols.
It's a myth that you CAN'T shoot lead reloads in Glocks, but it's not a myth that you SHOULDN'T shoot lead reloads in Glocks unless you thoroughly understand all the associated issues and risks and how to deal with them.