My guess is probably both to free space from their servers and to ensure that unknowing users aren't downloading an app that doesn't have somewhat recent security patches.
For searching in Hacker news, I saved the URL 'https://hn.algolia.com/?query=%s' with the search key 'hn'. So when I want to search something around here, I just type
hn something
which then replaces the %s variable with 'something'
https://hn.algolia.com/?query=something
There is Javascript code that allows for two or more arguments, but saving that as a bookmarklet isn't as neat.
Partially but no, it’s comparatively pretty bad after playing with it a lot.
It seems to be based on a much older and more literal algorithm where it buries a relevant post on page 3 just because the keyword was not perfectly in the title.
Probably intentional or they just don’t prioritize since a small % of people use it.
Better to use “site:” search for your fav blogs instead.