I've seen this too, and I've heard this from several gunsmiths. But the problem isn't the Frog Lube, the problem is that people often use way too much of it. Part of what makes Frog Lube work so well is that it's a paste and it stays on the metal better. But that means that when people over-use it and glob the stuff into their guns, the excess won't run off the gun like a liquid lube will.
When used correctly, Frog Lube is the best lube I've ever used, hands down. I recently did a 500 round torture test with my Glock 19 and my Octane 9 silencer. We loaded up a huge stack of G19 and G17 mags and went to town, shooting as fast as we could shoot while still staying on target. The silencer and the metal parts on the Glock got so hot that they melted an oven mitt. The guide rod on my Gen 3 Glock even melted a little and now the end is slightly crooked, but it still works fine.
But after everything cooled down and the Glock was finally safe to touch, we took it apart. The insides had a thin coating of carbon and Frog Lube, and everything was still properly lubed with no gumming or excessive fouling. Keep in mind that a silencer puts way more carbon back into the action, so shooting suppressed dirties the gun at far more than double the rate than it would unsuppressed.
I put my regular non-threaded barrel back in and put a bunch more rounds through the Glock just to make sure that it still functioned even though the cap on the end of the guide rod had melted and was now at a slight angle. It worked fine. Then I just wiped down the outside of the gun and put it back into my normal carry rotation. Frog Lube is good stuff.