Difficulty of normal content.

[VioletCatastrophe]

DT is consistently harder all across the board, there is no escape.

The game getting harder over time isn't a bad thing. It's easy enough. Most people aren't complaining about it. Even the non-raiding casuals are outnumbering you. Also there is an escape, it's called improving over time. You have no examples in your original post. I can't even comprehend what it is that is bothering you/the hypothetical person that is absolutely not you because you aren't struggling at all clearly. The examples you gave are nothing special.

The mist dragon punished you for failing its mechanics. Just don't hit it when it is mist.
Amaurot was 'don't stand on the cracked platform'. Otherwise yes, it punished you for failing its mechanics.
Tower of Zot is a little over the top, but the damage on the trio is pretty low so even if you get hit by a bunch of random stuff as long as you dodge most of it you'll be fine.
The final days wasn't that hard, though yes, it did have a boss that punished you for failing its mechanics.
Yiazmat is a boring damage sponge. Your complaint isn't about difficulty, its about alliance raids being objectively the worst content in FFXIV.
E5N was... don't stand in the danger zones or you die? It was pretty self explanatory for the most part. I don't remember anyone having issues with that, it was mostly E7N that tripped people up.
P2N also was a non-issue. The only boss I remember people struggling with on that tier was 3/4, and one of those was just because of the awful color scheme.
O11N might be a little weird, but there are also visual tells. The issue here isn't the mechanic, it's whoever the hell chose starbord and larbord (itself an extremely antiquated term compared to port), IIRC the original JP just had it as left/right.
Golbez I don't remember having much either. Just another trial like any other. Barbariccia was probably more prone to killing people. Even Golbez EX had more or less a single mechanic that actually walled people and the rest of the fight was largely rote. You can check contemporaneous guides to see what the attitudes of the time are for the EX if you think I'm exaggerating.

Of everything you mentioned there, the only one I'd say was probably a bit too mean is the final boss of Zot, and even then I wouldn't say it was beyond the pale. It seems like you've been struggling with content this entire time since stormblood and rather than work on improving you have blamed the content itself and done nothing about it. You are seeing the consequences of that here. If you don't work on improving as a player over the hundreds of hours that one plays over 3 expansions, you will only have yourself to blame if you get left behind. It's that simple. I'm not being mean, or an elitist. I'm giving you a reality check.

[Smoozie]

O11N might be a little weird, but there are also visual tells. The issue here isn't the mechanic, it's whoever the hell chose starbord and larbord (itself an extremely antiquated term compared to port), IIRC the original JP just had it as left/right.

Nitpicking, but JP does use the same nautical language, Starboard - Ugen (右舷) and Port - Sagen (左舷) rather than Right - Migi (右) and Left - Hidari (左), now the astute among you will probably have noticed why the difficulty of reading the mechanic didn't translate and why this is nitpicking.

A much "fairer" localization would've been Rightship- and Leftship- [mechanic], as that's what the Japanese more or less literally translates to.

As I said, nitpicking as I agree with the sentiment.