Storing the dislike counts for each user takes a binary state at the minimum, and a byte of storage typically. Considering the HUGE global user base, that would be too much data storage and maintenance required for a company like Google/Youtube to invest their resources in. It also improves user experience by minimizing the data transfer requied to consume products in the platform, thus improving the efficiency and speed in the platform.
It is for the best of the users, and is a great design for the user. User's will learn to love them in time.
The call to curl is missing a closing " pair. Besides, it seems some people submit a low-res image at the post, then post another link as the first reply, which is the case today:
It is a pity that DjVu[0] wasn't even mentioned; an open format that was superior to PDF in many ways[1], including better optimization, efficient storage.
If it is your own project, which doesn't depend on other's, then you can simply change it anytime you like if you decided GPLv3 no longer suited your needs. It is typically problematic when you are using someone else's program released under GPL; they released it under GPL hoping for what GPL entails.
You may also read this thread in the mailing list [0]. I may need to look up some more resources, but it seems to me that there wasn't a rigorous peer review for it. For example, compare it to merging SM4 into OpenSSL [1]. I would've thought that you'd need a few rounds of back and forth reviews mostly focused on cryptography and implementation such as possibilities of side channel attacks etc., not just some comments on style once.
