Bill Zebub
“It’s probably Matt Mercer’s fault.”
Without multiclassing though, "magical street thief" requires you to be a Wizard who can pick locks and stealth. Or wait til level 3. Or have your race choice locked.
Seems to me that's quite a few options.
(Also, vHuman Rogue with Magic Initiate feat. Or Bard.)
Going with the sample set of: a) the people I play with, and b) the builds I see posted on forums like this, I rarely see multiclassing with bad mechanical synergy that's done just for the concept. Almost inevitably there's a power thing going on.
And not that there's anything wrong with going for power, I just wish people would admit it and not claim it's for "the concept".
P.S. To elaborate, I think it's fine to start with a cool set of mechanics and then rationalize the concept, but let's just be clear that mechanics drove concept and not the other way around.