Does having more PoPs globally help optimize my page load times?
Back in the old days when we were using dial up modems and 3 and a half inch floppy disks, more PoPs was better. In those days CDNs were the right way to navigate the problems of low bandwidth into and out of hosting centers and between network hops. These days, it makes sense to run PoPs as close as possible to the Internet backbone to take advantage of the reduction in time required to make the multiple hops between network devices. Fewer PoPs also means fewer PoPs to fill with your content. Therefore, you will experience a higher cache hit rate for your content and ultimately more offload and faster retrieval of the content; which is what you were hoping for in the first place.
There is, of course, a balance to be struck between the number of PoPs and the global spread. Given the average number of requests to build a webpage these days is over 100, it makes sense to reduce the roundtrip time by serving content from as close as possible to the users. Note that closeness in this case should be measured in terms of Network Latency, not proximity (although proximity is a factor contributing to latency)
More modern CDNs provide fewer PoPs closer to the Internet backbone. The next generation of CDN provides you the opportunity to select the number (and location) of PoPs which is right for your application and audience.