In music, repetition legitimizes; in Star Trek, Spock legitimizes.
(Full disclosure, I've watched many Adam Neely videos but haven't actually watched the one above.)
Spock has been deployed again and again when Star Trek has "pushed the envelope". When JJ Abrams wanted to launch a new Star Trek film franchise, he brought in Leonard Nimoy to have Spock pass the torch. When Alex Kurtzman wanted to launch a new serialized streaming Star Trek series, he wrote it about Spock's sister (with Spock's father appearing from the first episode), and brought in Spock himself in the second season.
And when they needed to make the big swing for the fences and literally do a Star Trek episode where everyone is singing as if in a musical, who is the very first character to sing? Yes, of course, it's Spock.
The first Very Short Trek episode, "Skin A Cat", continues this trend. In this, Paramount's first officially non-canon official production (and debatably their silliest slice of Star Trek yet), the only character voiced by their "normal" actor is -- yes, you guessed it -- Mr. Spock.
Whenever the in-universe era permits, Spock is consistently invoked whenever Star Trek breaks new ground.
We can even extend this analysis retroactively all the way back to the beginning: when Star Trek was "rebooted" for the very first time -- after "The Cage" was rejected, and the premise reworked into "Where No Man Has Gone Before" -- only Mr. Spock and the Starship Enterprise herself were carried through into the new version, creating a lineage that indelibly legitimizes "The Cage" as Star Trek, even in spite of massive changes otherwise.
(And indeed, the Starships Enterprise play a similar legitimizing role across the franchise -- if an Enterprise appears, it's Star Trek.)
So, here is the question for us: why does Spock enjoy this particular ability to reify something into being Star Trek? Why is it he -- not Kirk, not McCoy -- that gets called on when the showrunners want to "bulk up" on their Star Trek bona fides? Why is it that, if Spock does it, it's Star Trek?