but I look at a mortgage and think “that’s 15 years I’ll spend paying back, at absolute minimum. Probably more like 25 years”
Yes! Probably more like 25 (or even 30 years)....at the same glorious fixed payment for that entire time! How many dozen times has your prior housing payment, rent, gone up? Now, it doesn't. The bank will never ask more from you on principal and interest in the future than it does on that very first mortgage statement.
When I bought my first house I was paying $800/month in rent at an apartment and the mortgage payment was $1000/month. I sold that house 17 years later with the last mortgage payment still being only $1000/month. I checked back on my old apartment to see what the rent was: $1400 for the same apartment I used to pay only $800/month for.
Also, you're not forced to keep that house you're buying for 25 or 30 years, but when you leave, its YOUR choice not the landlord's. When I sold my house I pocketed over $135k in profit because the housing value had gone up in that 17 years.