If this was one play in one preseason game, I'd be on the same page. Unfortunately, it's been a problem for years at this point whenever Zion's been available, and it happens for entire halves at a time, consistently.
It's fair to say that maybe that's because Zion's been out so much, so guys are more used to playing without him - that's fair. It's also fair that maybe in situations that are late in games, or on long road trips, or whatever, guys get tired and they start to default to what is easiest on their mind, which may often be isolation ball, since they can do that largely on autopilot rather than needing to watch the rest of the floor.
It's not acceptable in the first quarter of the second game of the year when nobody has played even 30 minutes of NBA ball yet - or in October at all, to be honest.
You can act like it's just pre-season, or just a few plays, but it's a scheming problem which is obvious; and it doesn't just impact Zion. It happens to JV as well; he can have mismatch after mismatch, score points every time he catches it, and they'll still just ignore him for 8 minutes at a time. It's not good basketball.