Because passion doesn't necessarily equate to skill. Passion looks like an eagerness to be immersed in a topic and invest time in that topic. Some people work out of necessity and not necessarily passion (maybe just passion to make a living, pay the bills, and support their families).
What actually matters is that you:
- follow through with your promises and claims to your team or manager/boss/founder/yourself
- you leave things better than you found them
- you're reliable
If you adequately do those things, there is plenty of room for you, passion or no passion.