WhoTargetsMe co-founder Sam Jeffers argued that Facebook was "deliberately obfuscating" code, claiming that it would defeat plugin changes "within hours" of their release. Facebook, however, said the break in functionality came from a "routine update" targeting malicious ad blockers and scrapers that could reveal data to "bad actors."

Facebook certainly isn't averse to political ad transparency. It recently implemented its own systems to help trace the origins of political campaigns, and has even gone so far as to ban foreign advertisers during key votes in a bid to improve accountability. The plugin limitations might prevent third parties from tracking sneaky advertisers in ways Facebook can't catch, however, and it's notable that plugins like WhoTargetsMe are voluntary -- users know what they're sharing. Facebook clearly has to walk a fine line when handling data, and it doesn't always achieve a perfect balance.