Shouldn't this link to the player's spell save DC?

Spells assume the DC is the casters unless otherwise specified.
It's to save wordcount for the books

Correct, but in my experience it does not link the DC on the character sheet tool, which is not the case for other similar spells. I suppose I should have been more clear about that.

Not having a save is the reason why this is an 8th-level spell. 

It doesn't have an initial DC, but it does require a CON save at the end of the affected creature's turn. This is a minor matter, but struck me as a bit odd that it wasn't supplied as part of the character sheet, hence my question.

Yeah the spell save DC is the players Spell DC, as assumed with any spell that you need to save against

Pretty good for fighting high level spell casters, as it instantly breaks concentration.

Not having a save and it can't be dispelled. 

"Fall"

Finally a man of culture

Since the word leaves a creature dumbfounded can it be any word? 

The DC would be the based on the Caster. That's what the Con Save implies. 

So if the caster were to somehow get a DC-21 saving throw, they would be capable of permanently paralyzing a commoner. That's horribly evil.

If you were to tag a raging Barbarian with this spell, would their rage drop from the stunned condition?

RealMelonLord, who in the world would waste an 8th level spell on a commoner? But actually, yeah, you're right...

This spell is on my list of banned spells.

Well, it's not on Mercer's. RIP Keyleth.

Why would you ban the spell? It's a great tool and they have to use an 8th lvl spell slot for it.

This is how I want to use it. That scene was so intense!

there's no resist for a power word spell