I do that as well. We found separate categories created a lot of admin busywork moving things between categories, and user confusion as they might search in the wrong category.
Users often think they’re making a feature request when the feature already exists and they really just need help finding it.
Other times they assume something’s already possible and ask for help in how to do it, when it’s not possible yet and their question is really a feature request.
Similarly with bugs, which often aren’t.
Now we’re on Discourse I did add some feature-request and bug-report tags to our Help & Support category, but to be honest I mainly did that to encourage people to use them instead of putting huge prefixes on their post titles. The tags are still often wrong and need changing but it’s a lot quicker to change them than to edit titles, so it’s a lesser evil if people insist on categorising things even when ~50% of the time they’re wrong IME.