Minor compactions will still be triggered whenever a size tier gets 4+ sstables (for the default compaction strategy). So it does not affect new data.
It just takes longer for the biggest size tier to get to 4 files. So it takes longer to compact the big output from the major compaction.
Assuming your data roughly follows a generational model, where newer data is written to often and older data is mostly read from. This can mean garbage hanging around in the big old file and *potentially* slowing things down.
I don't think that statement is accurate.
Which part ?
Probably this part:
"After running a major compaction, automatic minor compactions are no longer triggered, frequently requiring you to manually run major compactions on a routine basis."
From what I read what happens is that it takes a lot longer for minor compactions to be triggered because 3 more files with the size equal to the compacted one have to be created?