[1] https://moxie.org/2022/01/07/web3-first-impressions.html
There are enough reliable methods to not rely on trusting some random server, but some money hungry developers cannot be asked to implement them.
Similar to how some websites do silly things, like storing plain-text passwords in their databases. People do it, but it doesn't make it right.
Why? This is an unsubstantiated claim. Blockchains still have an outside body that you're required to trust, several in fact. The most prominent one is the miners.
I can't tell what the admin issues with your sale were because you didn't mention them, but it seems like being able to see the validity of the claim wasn't the issue that took 6 years for lawyers to resolve. You can show them the validity in person on the day of the sale.
When any of these deeds, titles or certificates are lost, burnt or stolen. You have to rely on an outside body to keep a backup safe for you.
Blockchain allows us to be super efficient too. Which is a perk. Rather than the need of waiting for someone to certify, deliver, inspect, notify, return, process. Depending on the industry, this could take years. Blockchain tech allows everyone to see the validity of a claim in real time.
My family sold out family home a few years ago. It took 6 years of unnecessary admin work to get it sold. If we relied on blockchain tech, it would've been processed in a day.