I generally don't do modifications like back plates or ejection port cover but know many people who do.
No idea what the utubes stuff was about, I found some time ago it was mostly some numb-nuts droning making a video just long enough to earn money.
Millennials eat it up it and spend money seems.
Your mention of ejection ports made me chuckle in remembrance of that Arizona cop that could not resist wasting the guy lying face down on the hallway.
Seems he had one of those custom covers that said (from memory) "you are fµcked'
Seems a decent prosecutor would have correctly nailed him as a loose cannon looking to waste a civilan.
But, being a polices, no harm, no foul for telegraphing his eagerness to kill someone.
Firearm mods may or may not matter depending on your status in the eyes of the all powerful state.