Most certs do indeed prove only that you can answer multiple choice questions. However, there are certs that truly matter, but not from skills perspective (although that helps).
CCIE is a good example, since it requires the lab part (I know some folks actually try to do the lab part by rota, with several attempts, but it's still rare). Some others might be the architect-level certs from Microsoft or Oracle. CISSP is a bit in the gray area, it's not a vendor-specific cert, but many customers actually appreciate it.
Anyway, while the highest certs may "prove" something about your skills, the biggest benefit is actually in something completely different. If working for a vendor partner (Cisco, Juniper, Microsoft, whatever), they typically give you status levels based on the number of cert-holders in the company. So basically, if you have a good enough cert, you can waltz in and say "even if I come here to watch porn every day, you can still pay me and save money". What it really means that even if you are a slob who has just gotten the cert by rota, the company can afford to pay you due to the vendor discounts. If you actually know what you are doing, even better.
I mentioned the CISSP, it's an example of a cert where having you on the payroll does not mean discounts from vendors - but it might give the company a possibility to enter higher-paying projects. Many RFQs usually hand out points based on what certs the people involved actually have.