We should not consider every problem in this format in a running competition.
These competitions generally runs for only a few hours. After they end, they are just exercises. They may still maintain a scoreboard somewhere, but it is not much different from PPCG upvotes and reps.
Some websites don't like people posting code in their own forums or something. But I assume that's just for not making it too easy. I doubt any of them will ban discussing the algorithms, or interfering with other websites, as long as it is not in a running competition. (If they really take it too seriously, it's really their bad.)
If they are really running competitions, it's unlikely they will get it satisfying our rules and receive an answer in their acceptable languages in time. Some websites even have mechanisms for detecting cheating (mostly for similar submissions in their own sites, and has no effect on copying the algorithm, though). So I don't think it is too much of a problem if we didn't notice some of them, yet.
It could also be a homework problem. But any problem could be a homework problem.
It could only annoy us for not satisfying the rules and unwilling to change. I don't know whether there is more we can / should do for this. One reason I could think of is copyright.
But if we don't find anything feasible, we could usually still just close them and/or asking for changes for the normal reasons. We could ask for its source and tell them copying the algorithm problems without modification is the reason it probably won't satisfy the rules, and sometimes uninteresting, but don't get distracted from the real problem, namely not satisfying the rules itself.