Are you using a phoscon coordinator? ConBee 2 has a lot of firmware problems in my experience.

There are also some devices which advertise ZigBee compatibility but the manufacturers don't seem to test them against coordinators other than their own (and ConBee 2 seems to have the most problems in this regard).

The protocol is complex, they all are, implementing it correctly isn't a given, but I think the issues people have are more often a factor of how long a protocol has been in use than any fundamental aspect of it.

As soon as cheap hardware manufacturers get on board you get this problem.

Quality hardware works fine with ZigBee. It's by no means perfect technology, if you want that, use copper wires, but it doesn't work as badly as you claim if you are not unlucky with coordinators and devices.