The Haas effect is one of the most dangerous things ever named by Haas.
That said - Back in the day, I was kind of a big fan of getting that ultra-wide kit sound -- I'd delay one of the mics maybe 7 or 11ms and the other by 13, 17 or 19ms (notice the prime numbers in there...?) to get that "Kill Em All" room.
THAT said - It's still "fake" -- It was typically better to move those mics out in an uneven fashion. Although it wasn't always possible. So delay, with constant consultation of the MONO button, was the usual workaround. Or a wide overhead and much smaller delays or a delay on only one side, which was especially tricky.
THAT SAID - As mentioned, it can be nifty on some things (an obvious pure stereo source, such as drum overheads or a discrete LR on a keyboard or room mics on BGVox, etc.) but absolutely terrible on others (a full mix for example, a mono source to be split without some sort of modulative effect on one source, etc., etc., etc.).