Not ignorant. They just might be pointing out the holes in the argument you are using because of the fact you cannot possibly know the outcome if SE added an official parser; last time I checked humans cannot foresee the future like in myths and legends.
If they did add one probationary, to test it, and suddenly the game had way more rude people than now, specifically using the official parser to harass, then you could claim you were right, but...how can you claim it yet? It hasn't happened.
There are people who are anti-parser that actually do demonize anyone who uses one even if said person never uses it beyond their personal use and never harasses anyone. I mean you have someone in this thread alone who basically reports anyone they 'think' is using one; harassment or not. So you might not be realizing that some people may be defending themselves on this point and not actually claiming that no one is guilty of toxic behavior.
The real question is would that toxic behavior still exist even if the parser didn't?
A parser is just 1's and 0's in a computer, that doesn't turn someone into a jerk all on its own. So toxic behavior is present even without a parser (all of the toxic behavior I've seen while playing this game was nothing to do with parsers and I've been playing for 4 years for example).
The problem is those rude people you may have come across, do you think if they had no parser at all they would somehow not be jerks? We don't know and that's the problem with doing all this guesswork. If a player is a rude player then without a parser they may just find anything else they can find to harass someone with.
Harassment in any form is against ToS so it really isn't any different than now. An official parser does not mean "you have permission to harass".
I posted this in another thread and it basically explains the problem with the argument of "if you add an official parser people will harass more with it".