Right now everyone is encouraged to link by using any sort of archive system.

Making it mandatory, however, has issues.

First you'd need to make it a rule for people to only use an archiving system for site A or B.

Then comes a group who wants to add sites C and D but remove A from the list because reasons.

Then comes a petition from that group, that has some support from the community.

Then another groups comes that wants to add sites E, F, but remove C.

In the end, it's hard to maintain, might be unfair and or require massive investigation of websites, and can be seen as censorship of sorts. It's a pandora's box with many cons and not so many pros.

You can easily block any url's you want using RES or other systems. You can also set up ad-block to block adds from specific sites.

You can and should downvote an article for whatever reasons you deem correct (as long as you follow rediquette).

However, and as all input from the community, this will be considered, but very, very unlikely that it will be enforced.