I think the thing you're forgetting is that users have the autonomy to find an instance (or create their own) that doesn't filter that stuff out.

It also seems to me that instances do a good job of describing themselves and it should be pretty easy to get an idea of what they will/won't allow.

I have absolutely zero knowledge on deep sea submersibles but every bit of reporting I've read or listened to over the past week has said that carbon fiber is a very poor choice for a deep sea vehicle. Given its propensity to eventually delaminate, it is much more likely to fail over repeated uses than titanium or the other materials the industry uses (I've primarily heard comparisons to titanium).