Ah, a subject near & dear to my heart.
Simply: proprietary systems=increased profits.

I've seen this wave growing in the construction industry for years; everything is a system. Problem is, when the miracle system of today is replaced w/ "gen 2" and/or fails, your existing system is no longer supported and must be replaced- sometimes at great expense.
Clearly, this is true for many things today; it is the new business paradigm.
A fer' instance; I like vintage motorcycles. 3 or 4 years ago I came across a bike I'd been searching for online somewhere in Georgia. Price was a bit high but since the history was known it was worth the stretch.
Bottom line, seller would not sell it to me, non-local, because I would provide no residual income from parts sales & service in the months/years to come. This from a small shop.
My theory here is that with the current world population, read customer base, businesses truly do not need to cater to their clientele at all-revenue is done on volume. Ergo, the propietary system: why sell a ( fill in the blank ) only when you can sell every single component necessary for its use throughout it's planned limited life span?
Sad.