I'm operating three 10Gb Tor exits in a DC in Amsterdam. [1] It seems like a meaningful contribution. I assume the other operators who are not IAs have similar reasons.
[1] https://metrics.torproject.org/rs.html#search/family:38A42B8...
[1] https://metrics.torproject.org/rs.html#search/family:38A42B8...
In short, my reply was: maybe it's not illegal but you might suffer quit a bit by the time it's all cleared.
This is one of those cases where often the question is not whether your actions are legal, the question is whether you can afford the time and resource required, and in some cases take on the potential reputational risk, to successfully defend yourself against someone (commercial, law enforcement, political, ...) who says they aren't and tries to make you stop.