On Apr 24, 8:52*am, " wrote:

We all know that FIDE was founded in 1924 but did not take
control of the title until after Alekhine's death in 1946.

The USSR imposed the system for the world championship in 1948.
The rules greatly favored Botvinnik who had draw odds from the start.

On this matter I must basically agree with Parr. In his
autobiography, Botvinnik describes how he himself was the main author
of the regulations FIDE adopted for world championship matches and
challenger qualifying. I'm not sure whether they were then "imposed"
on FIDE, or FIDE just adopted them willingly, but either way Botvinnik
and his Soviet supporters got what they wanted.
Besides the regulations for title competition after 1948, they also
got what they wanted for the 1948 match-tournament. For example
Najdorf was not invited after Fine declined to play. This gave the
Soviets a 3-to-2 majority among the 5 players (Botvinnik, Smyslov and
Keres vs. Reshevsky and Euwe), making collusion easier than if there
had been another non-Soviet.
According to Bronstein, Najdorf was black-balled at Botvinnik's
personal insistence, out of spite for the way Najdorf drubbed him at
Groningen 1946.

Apparently the rematch clause was added later at his behest.

No "apparently" about it. It's a plain fact.