How did you define the actual "best books" ? I usually pick a group (Goodreads users in country x), scrape the books of all its users, and sort them by frequency: https://github.com/harjoc/goodreads-group-books
EG "best average" "most reviewed" "users in country + frequency" and such.
This doesn't even need to hit performance, as these queries could all run on a secondary SQL server, be cached in redis/whatever once an hour, or even day.
After all, this sort of list output doesn't need to be second by second changing.
So simple to implement, non-performance impacting, which makes it even more curious as to 'why not'. Likely, a UI/UX person thinks it will 'confuse' people.
(I know that may not be the case, but it seems to kill more sites, and more flexible functionality, than anything...)