I think they spend a considerable amount of their profits for staff writing up vague , B/S policies.

This sounds exactly like one of them.

Here's another that's always stuck in mind - I had an email from someone asking me to call them as to organise inspection of an item that I had listed on both eBay and alternate online site. They sent me their contact phone number via eBay messages. In this instance I really did message back and say as much as I'm open to inspection I can't send personal info via eBay messages, nor did I send them any info about alternate website posting.
So, item sells via other web platform, not eBay. During that day my eBay account was suspended with approximately 50-60 listings all deleted...not even accessible to retrieve. I then had all of my PayPal payments coming from eBay, from that seller account and around 7 others, placed on hold for 21 days...each and every payment received. There's no real explanation to account holder, it's just the deal eBay and PayPal have/had.
I was finally told by eBay that they have automated code scanning messages for things like phone numbers and email addresses. In my case the bot discovered the OTHER PERSONS phone number, and also saw that I ended the listing within 48 hours of that message being sent to me. Support also read my reply and agreed I did the right thing.... but still did nothing !

Less than happy I put it to eBay staff that they're only interested in stopping people from circumventing fees, and are not considering all circumstances. Then they pulled this out of their proverbial :

Oh no , definitely not. The reason we do this is prevent problems between buyers and sellers that can arise when either party has direct contact information with the other.

Just as others have said , I can see no other reason for eBay to charge the fees they do on postage costs other than trying to prevent people circumventing eBay fees. At one time it was a free for all of $1 buy it now items with extremely high postage costs... as to circumvent fees.

eBay had a loophole and people exploited it. I don't begrudge them their fees but I do think the way they go about it is unjustified.

Maybe they could have spent some $'s on code scanning ridiculously low sell prices and incorrect postage costs, but hey , that probably wouldn't yield the profits a blanket postage cost fee would.