Well, you're probably going to get a lot of varying definitions.
For me it comes down to, how long does it take to resolve a situation
within the rules. A "crunchy" system will involve some combination of:
- Frequency of needing to look up rules
- Length of time needed to read a rule
- Time needed to apply the rule
- Number of variables modified by resolution of rules
The stickler is that not every game will have all of them, and some people define some of these as "crunchy" and not others. So a game could be extremely tedious at one thing but isn't "crunchy" because it's good at something else. To me, it's ultimately a clock issue. If player says "I do thing" and then everyone has to stop for 30 minutes to figure it out, whatever they spend those 30 minutes doing, you might have a crunchy system. (It might still be fun, but definitely not for those wanting faster pace.)
But there's another issue, and I'm gonna point it out: You could have a "rules lite" system in that the generic core resolution mechanic is a single short paragraph but it
still takes everyone stopping for 30 minutes every time to figure out how to do thing. They're not sticking their noses in books, they're deliberating in confusion, so it's somehow better? Just because a game isn't crunchy, doesn't mean it's elegant.