Oofta
Legend
I've never seen anyone require flanking or anything similar. Sounds like you've had some bad DMs.DMs who are stingy with things like hiding in combat tend to be the same dm's who rule you need to actually flank the target to get sneak attack, or just rename it backstab and take the name literally and wonder why the rogue's player is confused by the the totally clear interpretation of the rules as written in the 1e PHB while the rest of the game uses 5e rules...
I'm only a little bitter.
In my games, if rogues try to get advantage (many don't care) they get it on a regular basis. Just not every round every combat.