Why would you need to enable IMAP ? It works out of the box. Every non-android platform uses IMAP to access your account (k9 mail, outlook, thunderbird, the iOS/mac email client, etc).
As a former K9 Mail developer I will say that the Google extensions to IMAP for Labels and OAUTH (neither of which are standards) are a pain in the backside that no email platform would have dealt with were it not for the fact they are huge.
(I did a spike development for OAuth and a separate investigation into Labels when I had some free time).
So they are definitely not nice IMAP citizens.
Oh and then there's the issues with Labels that their own documentation apparently gets wrong...
To be fair here, labels are a great feature and the default limitation of a letter existing in only a single folder is a dumb remnant of ancient times.
If it's still not standardized then the pitchforks are aimed in the wrong direction.
Because, IIRC, IMAP access must be explicitly enabled by going to Settings -> Forwarding and POP/IMAP -> IMAP access: (o) Enable IMAP. And I think it is not enabled by default.
(I did a spike development for OAuth and a separate investigation into Labels when I had some free time).
So they are definitely not nice IMAP citizens.
Oh and then there's the issues with Labels that their own documentation apparently gets wrong...