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Here we go again. The problems with technicalities... Ok, here it is - 301 does NOT lose any link equity passed through it. It's known and that's what the linked post and tweets are talking about. What me and @effectdigital are talking about is "downtime" after 301-redirecting from one domain to another. The value of domain IS affected. If you would redirect a page from your own domain to another, on your own domain, sure, there wouldn't be any loss in link equity, but there would be loss in page authority for the new page. Think about it like this - google ranks a page, because it "knows and trusts" it. All of the sudden, that page is not there, and just sends google to another page. Google needs time to make sure that it's the same page, about the same stuff, with the same quality. It never takes away the link equity, but the "trust factor" is not there for a bit. When it happens within the same domain, Google understands that it could be simple content move or URL change. When it's cross-domain, the reasons could be much different. From hacking to selling the website etc. So that's why the rankings and usually traffic goes down, but, after Google realizes that it's all the same, and all good, they recover. Hope this helps, and sorry for the confusion earlier.