A few reasons (all are subjective and personal),
Be the change you want to see…
We’re on maturity point of S curve.
Tax paying citizens are very low in number plus they have lots of thing to focus on. They are equally vulnerable at the same time also divided in the name of religion, caste, language.
Classified section is hook for this forum. If this section didn’t existed then I never joined in first palace.
I still think putting restriction on many topics makes this forum more relevant.
Have you figured out how to block the section you’re not interested in yet
That is the need of the hour for you isn’t it
Do you mean this forum should follow
“Jack of all trades, master of none”?
more like jack of all, master of one.
I’m suggesting you fix your problem and not tell us what we should be doing
That’s exactly what I’m doing - fixing the problem (by discussion), not handing out instructions 
Whatever create engagement is the moto.
Some old members are only interested in politics because they can’t keep up with technology. But they have their own share of contribution. Have you seen washing machine thread?
Some are only here because of classified section.
This forum have only few dozens (exaggerated) tech enthusiasts, so I don’t think whatever you’re saying is possible.
Please read older threads, everything you guys are saying has been said for last 1.5 decades. Seriously 
Engage with what you like, ignore the rest.
Well, TE has survived 20 years for a reason.
Nah, you’re not doing that.
People engaging in discussion are doing what they want.
Why are you getting in the way of that
The Categories view is cumbersome and it wouldn’t hurt to have a main topic or member filter for the primary feed.
At least people can engage in topics of their interest. Right now certain category of topics are simply overwhelming the main feed which is the primary access point for most if not all.
We can mute categories or individual sub categories if its getting noisy or annoying. This will remove it from all the feeds. (not sure how notifications will work for them)
But before muting them, if we manually add them to the sidebar, then we have a easy way to access them in case we want to check whats happening. This way they will not be in our main feed.
Leveraging the sidebar for easy access.
This forum was created for technical discussion. Allowing occasional off-topic threads is fine, but when non-technical content becomes dominant, the original purpose gets diluted. Keeping tech as the primary focus benefits everyone who came here for that reason.