Yes, there certainly is brand loyalty. Some of the reasons for brand
loyalty are:
1) You trust the vendor to notify you if there's a newer version with
important security fixes or new features.
2) You like the way this particular vendor packages the software. (What
it's bundled with, the install program, proprietary tools that are included,
cost)
3) You want a 'matched set' of tools, libraries, installation
directories, configuration options, etcetera.
4) You like the vendor's support policies.
5) You want the printed documentation the vendor supplies.
I'm sure there are others.
DS