This belongs in an answer only if PPTP won't actually solve the person's problem, and you're recommending something else because it will solve the problem.

Otherwise, it's best left as a comment.

Answers should, at minimum, answer the question. Something that doesn't answer the question should be in a comment, or not posted at all.

Suggesting not to use PPTP (for any reason) belongs in an answer only if PPTP won't actually solve the person's problem, and you're recommending something else because it will solve the problem.

Otherwise, it's best left as a comment, or perhaps as an addendum to an answer that actually answers the question given.