"Back in the day", we didn't sell our bowling balls. Once it was purchased and drilled, it was "yours", and would probably last as long as you did.
That began to change in the early days of polyester balls, but you still used to see lots of those with names on them too. Soon after the advent of the urethane balls, people began to have them engraved less and less, as they started to get a new ball at MUCH shorter intervals than before. I knew a guy that had the Black, Gold, Grey, Blue, and Purple Angles. He always said he never knew he would use more balls in 2 years than his dad did in a lifetime.
Nowdays, balls are like toilet paper. Use it, get some crap on it, throw it away and get another. I don't think the shop here even has the old engraver we used to use.
My dad owned exactly ONE bowling ball in his life. I have 8 undrilled ones in my closet right now, and one I just drilled at the end of last fall league that doesn't have 25 games on it.
If you came to bowling in the last ten-twenty years, I can understand why engraving your name on your ball seems strange, but there was a time it was not all that weird.