As a (former) owner of a dogshit soldering iron, I think it makes sense. People with weaker irons struggle to work with unleaded solder and tend to write it off entirely mostly because of their equipment. If you have an appropriately hot iron, both types of solder will generally behave the same which makes it a bit of a no-brainer to use non-toxic solder.

That being said - leaded solder is easier to work with regardless of what iron you use. It's very easy to fix mistakes and even wicks up without a trace on most PCBs. I personally don't use it, but I think it's easy to see how people will blame their solder before their iron.