It is entirely possible to clear extreme fights and savage fights without third party tools or any UI add ons, because I've done it. Unless you count a notepad text file on my second monitor as a third party tool, which I don't because a PS4/PS5 user can also have a sheet of paper with stuff written down next to their screen.

I honestly think this is one advantage older players have over younger ones. I've played MMOs for 20 years, I've learned to live with crappy UI and limited information for decades. I learned to count to 30 on bard when that was my main in XIV, just like I learned to count to 30 on red mage back in FFXI.

Would I like some improvements? Absolutely. I could not make my debuff button big enough when I was progging P1S. I'm on a friggin 2K monitor and even the largest debuff bar setting is about half the size of what I would like. I had to learn to stare at the spot where I moved it for Fourfold Chains as the cast went off so I would know immediately where to run. It just took a bit more practice.