CVSS has consistent rules, but yeah then incentives that make people ignore particular rules (vulnerability chaining being the one that I’ve seen before) makes the public scores questionable sometimes. Still it’s a useful, if imperfect, tool in our industry I think.
No, CVSS does not have consistent rules. Even people who support CVSS don't claim it's consistent. It's deliberately designed so that organizations can make it say what they want/need it to.