I like your question. Ok, you can use 500px, Flickr, Google and other sites... But... In my personal opinion, a developer should be curious. I'm a dev and, for this reason, I like to give myself a challenge. It's a good way to learn a lot, to discover new solutions, to meet new people, to improve my skills, to create something new. So... you can use Google Photos library or you can consider to create something different (because definitely your solution will be different from the others). It's a choice ;)