There are plenty of Canon lenses that don't have OIS, e.g. the superb EF 180mm F3.5 macro, which has no OIS equivalent in either the EF or RF range.haha. I admit I did experience similar albeit milder rollercoaster of emotions about the IBIS. I calmed down when I realized my lenses have Optical IS. And I can use them without IBIS. R5 won't let you use OIS without IBIS.
... and when it comes to third party lenses, there are even more that don't have OIS, including the entire range from Laowa.
So while *you* may not own or need such lenses, there are plenty of us who do, and for us, IBIS is extremely valuable.