Fair, though I believe this makes DM more powerful than expected: it essentially dispels all spells on a caster and an effect, rather than one or the other.
And to respond to your previous post: there’s a difference between a character attempting to issue commands to another creature; and a spell granting the effect that whatever a character commands, it is flawlessly followed.
You’re equating those two things as equivalent when they are not.
The magic of the summons/conjure spells ensures commands are followed that are issued by the caster. That’s not the same thing as trying to convince a creature to your wants through RP.
What exactly is a caster Concentrating on if not the spell?
If there's no magic linking the caster's abilities to the spell, why does losing Concentration affect it?