When including the raw flat probability its really only in there for the true statistics nerds.
realistically due to the fact that one save stops the chain of saves CC will trend very strongly towards multiplicative numbers but here they are.
At the lower levels we are looking at the comparison between hold person and stunning fist, war priest honestly can cc earlier at lvl 3
giving it an even better advantage wizard and warlock blow both out of the water between sleep(no save and very likely to sleep at least one target)
and access at lvl 3 to hold person as well. if you want the numbers on them i will post them but they arent super relative to the discussion because warlock sorcerer
and wizard should out perform these two by a landslide that's much more their wheelhouse warpriest is a much better example because they share the same hit die
the warpriest is tankier by ac and out parses in damage. TLDR it also outparses in CC as well.
there is also a slight untouched subject in regards to cc as well in my numbers, monks have to match thier cc against constitution saves and it is demonstrably more likely a monster has a high con save instead of a will save for warpriest.

Relevant Class lvl 5 Stuns Chance to stun on median save(+0) Chance for a stun to perpetuate 1 time(2 rounds) Perp 2 rounds 3 rounds
Monk -------------------------5 55.00%---------------------------------------- 0.00% ------------------------------------------------------0.00%---------- 0.00%
War Priest ------------------9 55.00%---------------------------------------- 55.00% ------------------------------------------------------55.00%-------- 55.00%

----------------------------Max targets CC-able in one round Total average rounds of CC
Monk(continued)----------------------------3 ----------------------------------------1.5125
WarPriest(COntin)-------------------------2----------------------------------------- 19.8
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Relevant Class lvl 11 Stuns Chance to stun on median save(+0) Chance for a stun to perpetuate 1 time(2 rounds) Perp 2 rounds 3 rounds
Monk -------------------------11 55.00%---------------------------------------- 0.00% ------------------------------------------------------0.00%---------- 0.00%
War Priest ------------------16 55.00%---------------------------------------- 55.00% ------------------------------------------------------55.00%-------- 55.00%

----------------------------Max targets CC-able in one round Total average rounds of CC
Monk(continued)----------------------------3 ----------------------------------------3.3275
WarPriest(COntin)--------------------------3------------------------------------------35.2
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

The numbers you are seeing for monk are so low because monk has to go through a double nested check to get their effect off they have to spend the Ki point pro actively before they strike and its wasted if they miss. then they have the two comparisons a hit roll and then the enemy gets a likely very potent chance to con save out of the effect. Since almost every opportunity to do something in D and D 5th ed is about 50%(designed by poo throwing monkeys) thats about a 25% right off the bat assuming you get the same chance on save as a cleric throwing at wisdom saves instead, which is incredibly unlikely. these numbers are so skewed towards the monk its ridiculous and they still cant even compete with an adjacent damage dealer/support/tank that beats them in every other category. at lvl 5 the warpriest has almost a 130.1% CC advantage, and at level 11 its even staggeringly higher than that.