https://youtu.be/eM-rJWBuWhw this is a great video if You want to learn about seating your ptfe tube and heat creep
there are a couple of videos out there that refer to the screws in the Creality hot ends. CHEPs video did a really good one and used a thermal imager, proved decisively that the screws do not affect print quality.
From my standpoint, i never understood why people would think those screws would propagate heat creep. If the design of their hotend was that bad i dont think they would be as successful as they are. I have run into heat creep myself, but i dont have an ender 3 hotend, so it was a user error, and a mechanical failure of the quick release fitting.
Good to point it out though as its a common enough issue to troubleshoot.
realistically the purpose of the screws is to assist in changing the nozzle.
they help to hold the block in place when you have it hot to re and re the nozzle. Slice is doing it on all their hot ends to facilitate “one-handed nozzle changes”
not sure who did it first but personally I like it