This is really a question for the devs. I'm just another user, but I can make a pretty good guess.

The idea isn't to create an isolated silo, and I can see situations where a link would be useful, for example if you are referencing a peer-reviewed scientific paper.

However links can be dangerous things, and it would harm Reverio's reputation badly if it started filling up with links to malware. Showing the full link rather than making it clickable can help somewhat by showing the actual destination (although it's not foolproof).

Just as important is that answers on Reverio should be written to directly answer the specific question being asked. It would be far, far too easy for lazy people to answer a question by just pasting in a link to anything on Wikipedia or Quora that is vaguely related to the question. The problem with that (apart from potential copyright issues) is that it just fills Reverio up with responses that are low quality approximations that may not accurately answer the actual question being asked.

So I get that being unable to create a clickable link can be a bit frustrating, but I can see the logic in it.