That first link is simply Nexus reminding authors that they can't bypass Nexus rules by having the rule-breaking parts off-site but linking to them from here. It's a reminder that such exploits are not allowed. It isn't a change, just a warning that enforcement is about to increase.
The second required no extra work for the mod authors and was necessary to make Collections work.
Support has no similarities. Nexus users are not kept from getting support by it being on a different site. They just have to make an account for that site if they want to use it. Nexus has no need to cater to "but my information...." complainers. If you're worried, just use fake information on the other sites.
As for how are they doing "double the work?". Maintaining two support sites with two bug report methods and having to answer the same questions over and over at both sites. Why should they have to do that so that you don't have to create an account elsewhere?
If you took the time to read the articles you would see what I mean. The first article is a reminder for you, to changes to guidelines that bothered modders age ago.
The second article is the most recent example, and there's is nothing about collections that spells useful and good for modding, most collections we have to date are untested and unstable, some of them have MODs that aren't even supposed to work together. So collections hasn't done anything to make modding easier (as Nexus states), if anything if only served to lose MOD authors over a useless feature that is causing more problems than solving.
The authors are not maintaining anything, answering the same questions is the bread and butter of every day author (is why some MOD pages have over 5 stickies).
Not to mention duplicate entries happen regardless of using one platform or two, and there are options available on Nexus to avoid that.
But honestly I don't wanna waste my day arguing about this, if Nexus wanna keep getting neglected is fine by me, we should deprecate the bug tracker that is never used (and wasn't even updated along the rest of the website) and restrict the post section to author FAQs since no one cares about feedback and support on Nexus.