I don't think they would do that either. First off, you will never read in ToS of any reputable gambling site that winning too much results in some kind of limiting your bet amount. Secondly, you can bet a low amount many times and voila, you are betting big again, right?
That fiat based casino you were limited on for winning just €100 wasn't an example of a good casino, if you ask me.
You are right that it is never written in the TOS, but there are quite a few stories here on this forum where people won big and can now only bet low amounts on several sports markets.
I only joined that fiat casino because they had a real good welcome offer but stopped playing after I got limited lol.