Re: It's good to have choice
Google blocking Outlook (as per this article) because their system is "more secure"
OAuth is not "[Google's] system". It's a standard created by Blaine Cook for Twitter and then developed further by others.
Personally, I have no use for OAuth - it solves a problem I don't have, because I'm more careful with my credentials than the people it "helps", and the attacks it addresses aren't in my threat model - and I dislike it for historical reasons. (I used to follow a few people on Twitter in case they posted anything important,1 but when Twitter started mandating OAuth that broke my preferred clients. I find that sort of "security by jackboot" particularly obnoxious.)
But at least Google give you the option of disabling it, which is more than some people (the Twits, again) do.
Oh, and it breaks Thunderbird, too.
I have Thunderbird working with two GMail accounts on another machine. I don't remember offhand if more-recent versions of Thunderbird support OAuth, or if I configured GMail to remove the OAuth restriction, or if I added an OAuth extension to Thunderbird. There were a couple of attempts at OAuth extensions for Thunderbird back when OAuth first came out; they were problematic, but may have since been fixed. Or the support may have been added to the base MUA engine.
1They never did, but the phenomenon isn't unknown, for example during natural disasters.