I have a bunch of different colours in my shed. The only appreciable difference I've noticed is that when I needed the service manual to fix something, the CaseIH dealer slapped a book down in front of me. The tech at the Deere dealer had to enter a password on a computer to decrypt it for me. Neither seemed terribly concerned about providing the information, though.
The tech analogy is basically similar to those who have their tech stack as Microsoft .NET vs Go. You can switch but it isn't as easy as just buying all new equipment.
Another point is JD is far more than just tractors so if you run a farm you will have many large pieces of equipment which you paid millions for so not so easy to just go and buy new stuff.
