This is all very fair criticisms. This thread asked: "What are tools you have made for yourself?" and that's genuinely what this is. I wanted it so I made it and then AI makes it so easy to just throw up a marketing page.

I've a a handful of dev friends that have started to use it as well and give their feedback and it's been slowly growing as I've added sharing/invites.

I would absolutely not recommend putting big production data into it currently.

My vision for it was something more like how the #1 use of spreadsheets is actually people making lists and not actually people doing lots of calculations.

Given the uptake today (thanks everybody!) and your feedback (thanks Mystery-Machine) I'm going to work at addressing your concerns.