Logging sites have an important function in making pug raiding more viable. The ability to preemptively understand if a given party or player is even capable, and thus worth investing the time in, is an important factor in avoiding potential frustration.
I do however think that certain categories on FFlogs should be opt-in; There's really no reason that that anything outside of content with hard requirements like ex/savage/ulti should be logged by default.
Making it globally opt-in would significantly limit its usefulness as part of the pug vetting process in high-end content. There's a decent chance it would lead to people sequestering themselves and refusing to allow anyone who hadn't opted in into their parties. As for causing toxicity "every single time", that's honestly just an absurd claim. ACT usage is extremely widespread, and it's an extremely small minority of users actively using it to hurt others. With most people who use it, you'll just never know.
I have over 10k hours logged in FFXIV over the years, and raid something like 4-5 times a week, usually pugging. In that time I can only recall three cases of actual direct parse toxicity, and I personally reported all 3 cases. The vast majority of toxicity I've encountered in-game has either come in casual settings and had nothing to do with parsing, or from insane Roleplay related drama.
A lot of people in the high-end community are tired of being unfairly demonized by a subset of the community that is frankly obsessively fixated on something that barely affects them in day-to-day gameplay. If you aren't doing high-end content, there's really no good reason to spend a bunch of energy fixating on this issue. This thread wasn't started by someone who wanted parsers to be allowed publicly; It was started by someone looking to stir the pot and frame people who use them in a bad light. That is the case with many of these threads, and posts on the subreddit.
If you were a roleplayer and people were constantly saying that all roleplay does is cause drama, and that all people that do it are bad people, wouldn't you feel the need to defend yourself and the thing that you care about?