True, but Adblock Plus is GPL:
https://hg.adblockplus.org/adblockplus/file/tip/COPYING
That qualifies as Open Source under any reasonable definition of the word [1]. So being Open Source is no argument for or against either Adblock Plus or ublock origin, because both are.
Re:Adblock Plus now sells ads
by y0ghur7_xxx on Tuesday September 13, 2016 @10:13AM
(#12488384)
The OSI definition of "open source" is not the only definition. I would argue that most people see "open source" as software where the source is "visible" (no data to back that up).
Then you have a gazillion of "Open source licenses", that can be less "free" to more "free", like BSD, GNU, MIT, Apache, the free source license, ...
[1]: https://the.bytecode.club/showthread.php?tid=147