There’s absolutely no reason to use it outside of nostalgia like you said or habit.

Portability, reliability, big buttons, big clear numbers, the possibility to review and double-check multiple printouts of long strings of additions & substractions, removing said printouts to store them with records as proof of accuracy etc Many benefits that explain why a large number of financial institutions and bean counters still use these printing calculators.

Accounting is a very conservative profession slow to change, so a lot of old school partners at firms still have those big old things on their desk. I worked with a dinosaur for a while who knew exactly how old and out of touch he was and didn't apologize for it. Guy would print things out on paper and bang out a bunch of numbers on his ten key that was older than me. He knew his shit though and was really darn good in his own way, just..really really old..but yes you are right there's no reason except nostalgia or habit.

I still use one of these at work. They can be pretty useful when showing work. I make the people I train learn it because I kept catching them hard coding cells in excel and when they do the calculation wrong it takes forever to find.

I use it for doing math with my left hand. Don’t have to move windows around or move my right hand from whatever it was doing.

Computer keyboards aren't optimized for 10-key data entry. The operations don't fall naturally to hand in the same way.