The forum does not delete members' accounts and they do not represent any problem - I see no reason why you consider it a problem at all?
And they shouldn't be deleted--ever. This forum is a huge part of bitcoin's history, and can you imagine if all of Satoshi's posts were deleted just because they're old? Also, if any of you have never browsed threads from back in the early days, I'd strongly suggest you do so, because they make for some
very interesting reading. I've spent hours getting lost in the topics that were relevant in 2010-11.
It is only someone who does not know the importance of history that we recommend that accounts should be banned when they stop being active.
At my leisure, I only have one duty in the forum which is to go back to the years before 2015 in the forum to read conversations in the technical and development board were Satoshi and early adopters wrote and discussed.
Another board is gambling discussion board, where I read about football and the history of it. It helps refresh my memories on what happened years ago.