I thought this quirk of Freecam stopped being useful many Minecraft versions ago. I used it all the time in 1.7 and 1.8, but modern Minecraft servers are so much stricter about which angle you place / interact with blocks from that it would just undo the interaction most of the time. This is very noticeable in InstaBuild too: most blocks in a template won't actually get placed, for the exact same reason. I did not expect so many people to still be using Freecam in this way in 1.21.11.