Blitz develops intuition and opening familiarity faster than slower time control chess just because of a larger volume of games at a faster pace. Most other things would probably tend to improve with slower chess.
I do not think there is any evidence for this assertion.
You might believe it. It might seem to be true for you. That does not make it true. One problem with the Internet is the huge amount of opinion presented as if it were fact.

Blitz develops intuition and opening familiarity faster than slower time control chess just because of a larger volume of games at a faster pace. Most other things would probably tend to improve with slower chess.