My feeling about this is that this top section on main page is aptly named "recent topics", so filtering FPGA or other "unrelated" topics is not a solution. This top section is just about recent topic, it doesn't mean "most important topics"
And even if this was done, who would define an "unrelated topic" ? Are Atari FPGA completely unrelated ? are emulators completely unrelated ? Do only topics discussing about usage on real HW deserve to be in this top section ?
As an example, if a topic starts with playing a particular game on ST, that's fine it would be in this top section. But what if later in the same topic people reports that this game doesn't work correctly under an emulator or under an FPGA clone, does this topic still deserve to be on the top section ? How do you handle this ?
That's real questions and I think deciding exactly what would be in this top section would create more harm than good, because it's obvious that in the end people will have different opinions and will want their own unique "top section", which is not possible with this php forum. Then people will leave, telling they weren't listen to, which would be sad.
In summary, I don't think a vote is needed because there's already a de facto vote by the users : they participate to some topics they like and those topics naturally get referenced in the "recent topics" section. If other people decide to talk about musics on ST for example, then it will appear in the "recent topic" sections.
So, as was pointed above, the problem is not that some people discuss about some "unrelated" topics to you, the problem is that no other people are discussing about what you would consider "real ST" topics.
It might be sad, but if no one feels like creating topics about those "real ST" topics, then it will stay this way.
Hiding "unrelated" topics in the top section if no one write recent "real ST" topics will be worst because each time you come in AF you will see that the top section is like dead : "recent" topics' date will become older and older as no one write new "real ST" topics.
And if people wrote "real ST" topics regularly, then problem would solve itself, it's all simple as that (IMHO
Personally, I like AF the way it is, because it discusses many topics about Atari in many different fields (there might be a few discussions about such or such fpga core , but honestly not that much and it's easy to skip them).