I do get that is just in my time of going to football the atmosphere has been a reflection of what is seen or done on the pitch. I can't speak for pre 90s but relative to the general expectations the atmosphere is a real live referendum of the feeling amongst the fans about the current state of the side. If they are excelling the fans are all happy and jovial, if we are doing poorly it's the opposite.
I guess we just come at from a different starting point but I liken it to the roman amphitheatres where the crowd would decide the fate of the defeated fighters.
The players will definitely be aware but it's a real life genuine response to how they are performing. Yes it would be great for everyone to not care or be affected by it and still sing happily but that's not how life really works. People's moods are affected by their surroundings and what they are experiencing. Football has always been a experience with a emotional taxation, that's why there is such exhilaration with a goal or success but you will get the opposite reaction when it's not working. So yes the players will hear but at least they will know the truth about how their performances are being perceived by their most important constituents. If they are affected I do kind of think tough brick because that's the arena you've chosen to take part in. You can't get all the praise and adulation without the flip side when it's not going so well.
I'm no fan of Johnson but I agree sending him personal messages on SM is dumb and not part of what I'm talking about, but criticising his performances vocally and live and direct at the match is perfectly acceptable to me. As long as again we are just talking about how they are performing, not calling him a clam, or doubting his parantage etc.