I haven’t tried setting up IMAP directly in mutt for a decade, so maybe Neomutt has made improvements, but it was often laggy to the point of being unusable.

I’d suggest people look into using mbsync (author mentions it at the bottom of the blog post as an update) as an external tool to sync mail via IMAP, or if you’re really committed to Gmail you can give lieer a try. It integrates well with Gmail’s labels and syncs them with a notmuch database. I stopped using Gmail years ago and switched to Fastmail. There’s an equivalent program to lieer called mujmap that works with Fastmail. I’ve been using it for over a year and works great.