Most likely so that the minister can brag how many applications IRCC has processed within service standards of 12 months.
Working on any applications that were in processing for 13 months or longer is absolutely useless for this.
I think it also works better to finish the most recent applications ASAP in order to bring their average processing time down. So, that could be why they favor 2023 applicants, not out of great love
I would not blame lower rank officers for any of this, they are doing what they are told. Their management is probably incompetent though, but I am not sure on which level.
It seems that there is no pressure on them to change these practices, even though 10s to 100s of thousands of applicants are affected by this every year (they just acheived 80% in 12 months this spring, if I am not misremembering).
Applicants from 2019 and 2020 were the hardest hit, since IRCC just didn't work for several months, and their 12 month window has passed, so a lot more than 20% of these applications were abandoned for years.
Either the affected group is not very vocal, or the problem is not seen as serious enough compared to other issues.
If you go way back on this forum, you will find that a similar situation happened in early 2010s: there was a huge backlog of old files that were ignored in favor of the new ones, and were stuck for many years. I guess in IRCC nothing ever changes...
For 2022 applicants things are not so bad, it seems that many get finished in 12-18 month. So, there are some grounds for optimism.