I've put the numbers so it's easier to discuss.
1) Please see below. Even ITAs given this year are below the target. It is said that about 20-30% of invitations results in rejection. I expect that to be lower among CEC, so say it's about 10%. We're looking at 10,000 rejected out of 102,000. Even if IRCC manages to give PPR to every single unrejected ITA sent this year, they're still at 92,000 as of today. Got 15,000 more to go.
2) Refugees and Parents don't factor into "economic immigration" and thus have a separate quota. Canada's main interest is in economic immigration (google why if you're curious).
3) If you look at 1) you'll see 2021 targets are still at some risk. Now think about 2022 targets which are greater than those of 2021. If IRCC does what you said and waits till Jan to process FSW apps, they're never gonna meet 2022 targets.