Nobody in any of Gaeltachts uses any of the Irish words with "th" in them? That doesn't sound right. Go raibh maith agat agus go n-éirí an bóthar leat.
I was pointing out that there are contexts (such as signage) in which they often don’t. It is possible to write perfect Irish without ever using a TH. For example:
“Go raiḃ maiṫ agat agus go n-éirí an boṫar leat”.
There are indeed books you could open and not find a single instance of it.
Ahh, I misunderstood what you were saying. Thanks for clarifying
Admittedly it's been a while since I've read an Irish book (or any book, audiobooks are more convenient for me) but I'd never come across anything modern that used the dot throughout, only in much older manuscripts or the like. Or stylized writing for designs. Signs are a good example.