Nope, not complex at all. Before the pandemic, there were consistently all program draws, with the odd program specific draws for PNPs and FST. You have to go back to 2015 i believe for the one CEC exclusive draw done previously.Its a complex situation so no one factor is responsible for the current trend in the draws. If its only about the CRS score, they would have suspended the draws. IRCC is well aware of the stuffs like how much time it takes to process the application starting from ITA issued or who are more deserving.
From IRCC twiter-
We can confirm that Express Entry rounds of invitations are still happening, and at this time, we are continuing to accept and process applications.
Travel restrictions are currently in place for anyone approved for PR after March 18, 2020, but a candidate invited to apply now will likely not have their application processed for at least 6 months.
Recent CEC-only and PNP-only draws were meant to benefit candidates who are already in Canada with a temporary status. Processing of permanent resident applications is continuing.
As soon as the pandemic occurred, there were only CEC and PNP draws.
Cause and effect.
As soon as the pandemic abates and it makes sense to resume all program draws, that's what they will do.
Again, it does not make sense long term to invite CEC candidates who are sub 450 while there are FSWs with scores in the 460s, 470s, and 480s.
It's not meritocratic, and it disenfranchises people who have just as much a right to apply for immigration as candidates already in the country.