You can still modify and save a few minutes after posting, I presume the goal is to avoid that people edit old postings to fit their current narrative
Right, but something has happened recently to the ability to modify posts. For example and not that long ago, I was able to modify an old Marketplace post of mine, but no longer can. For the longest time I could not (which made a complete mess out of the sale thread), then was able to. I thought great, they finally fixed that, but the option to modify is broken now again.
I think you should be able to modify posts in the Marketplace indefinitely. Especially when wanting to update your current goods for sale/trade.
Sure, put a time limit on all other posts if you want (few days maybe?), but losing the ability to modify (say you catch a misspelling, left out details, etc.) right away after logging out, then back in again is strange IMO.