...and those who were dropped out from those organizations then faced serious problems at school, work, etc. .
I see what you mean. I just want to point out that even though there was some pressure in certain situations, things were more relaxed in the USSR than many people believe.

My cousin refused to enter Comsomol (I think it was not because of any political reasons, more like he liked to act out at this age). There were no problems whatsoever. Zilch. Of course, his teachers were shocked at first (things like that did not happen often), and he and his mom earned a couple of lectures from them, but that was it. In a week nobody cared.

Moreover, my mom who worked in a high security engineering department refused to enter Communist party (being a Communist was not compulsory, but it could seriously help your career especially if your job was connected to military or high security stuff, and usually an offer to enter was accepted). She said outright to her boss who'd made an offer that she does not want to enter because Party meetings are boring and a waste of time. Again, there were no problems, she even got a promotion shortly afterwards.

I don't know anybody who refused to enter Pioneer organisation, though. Most of the 10-year olds (age of entering) were pretty excited about it, because it made them feel all grown-up.