I've had iPad applications crash on me numerous times - but I still think they're great, largely stable devices.
Just be careful dismissing products due to a singular negative narrative that you've created.
I'm not a blind Apple user. The recent MBP changes has me strongly looking for an alternative. I didn't make up my mind. I went out of my way to go to a Msft store and give them a shot. Nope, it failed. At the end of the day, the consumer most likely makes a decision based on anecdotes. There is no 'scientific standard' to 'should I buy a Surface or iPad'. There isn't. Being critical of my opinion is a sad thing. As, all I'm doing is sharing my experience and your attempts to 'refute' my perspective only help refute yours.
I'd encourage you to consider that I'm trying to help people with my experience. You sharing someone else's experience to 'correct' me is mean-spirited. Namely because your desire to correct and not inform.
How you approach saying something matters more than what you actually say, when dealing with humans. It's something that I'm learning as I've gotten older and I am not an expert.
For math - it's been over a decade, but I think I'd need a big device (ipad pro 12.9) and a pen. I'd want to be able to get a full page of notes on screen at once. That said, I'd be tempted. I've scanned my old notes for posterity and to save space, but it would have been nice to just capture them in digital form in the first place.
I'd also want a TeX stack on the device (editor+preview), but I'd write that if I had to. (I did pure plain TeX back in the day.)
The only draw back for me is that I haven't found a solid journaling app that I trust, so I still carry a paper journal.
I'm a math student. I hate the sheer volume of paper I have to lug around. I know the iPad won't replace 100% of my activities as a college student and as an autodidact but I have a sneaking suspicion that the iPad Pro is a solid device, localized control and overall a replacement of my laptop (primary computer) for 95% of activities.
P.S. I went to check out a Microsoft Surface, a family member got one for xmas last year and she loves it. It crashed on me within 1 minute, namely OneNote, which would be apart of my primary workflow. iPad Pro never crashed and had great response times.