As much I don’t like CAPTCHA, it is one of the few solutions to prevent bot (python etc) upload spams. Fighting against bot volume download, might as well auto prompt CAPTCHA once it hits over 10 downloads within 60 mins. Why download 10 times under 1 hour, or whatever Makerworld see what is the best setting base on data.
After that prompt passed, the rule relaxes for another X times because the system has verified a human.
Could be a idea, and you can even exclude accounts that have certain conditions.
For example accounts that did X ratings of prints to strike 2 birds with 1 stone and get others to rate the actual print profiles more then just enough to get the 50 free points at the start of the month.