Typing fast is a way to unlock the brain. Anything past 90, you start to focus on exactly what is needed to type accurately with speed.
I average around 106-130 (depending on recent races) for the past 15 years, and it's still one of the best ways to "get into dev mode" really quickly.
There are no real SEO penalties, but as with any web property, you have to do the work to get all the SEO working as you want.
As far as benefits for developers, give me an open source tool any day that I can improve on, extend, or mess up with sketchy coding. These tools are meant for consumers to build their own sites for the most part. They represent the initial commodification of "get a website". They are more difficult and/or expensive to extend than a tool like WordPress, Laravel, Hugo, etc. And they are walled gardens, which means they are difficult to migrate away from.
All 7 books come to ~1.75M tokens, so they don't quite fit yet. (At this rate of progress, mid-April should do it ) For now you can fit the first 4 books (~733K tokens).
Results: Opus 4.6 found 49 out of 50 officially documented spells across those 4 books. The only miss was "Slugulus Eructo" (a vomiting spell).
Freaking impressive!