There are discord bots that can cache information if the server owner wants to. And many people still make a website in addition like The Balance does. Beside that, discord has a way to find discord servers now.

Even if it was all cached, Google results have all been ruined by AI and all the reddit posts that come up for things are often outdated or misleading (ie. we have multiple fights featuring Titan and Shiva so it could deliver the wrong information to a new player). The reality is there is so much in the game, and it changes from time to time, that it's better to just ask a veteran player for the answer, which many people do in their FC, the Novice Network, forums, or on discord.

Discord is part of the internet now. It brought together refugees from lots of different chat and voice platforms - messengers, Skype, voice chat software, IRC, Steam, etc. They came from all directions to that one place and now it's part of the internet more than any of the others were. It became a platform for marketing by influencers, developers and businesses, and even used by schools. Even if SE reinvents its own version of Discord inside the game, people may not even use it. They use Discord for a reason. It was better than all the competition somehow and created a deeper feeling of community than the rest.

Trying to ignore Discord is like trying to ignore YouTube, Google, Facebook and other super popular apps. I suppose you can but... you know they are there, and you'll keep hearing about them.

People may not all be aware but Discord's co-founder plays FFXIV and made Discord in large part due to it. It was probably part of its success because making stuff go viral in the FFXIV community is especially effective and there was a peer pressure for raid groups and PUGs to install it over the other bad voice apps (every single one of those was trash).