Most debaters on modern day debate are trolls.
they are not interested in debating, but in personal attacks. For example, instead of responding to argument, some will say "He is probably from India".
And some are even worse trolls who pretend to support something and then turn against it in middle of conversation, pretending to be "convinced" (I have seen same person do this multiple times on same topic in few days).
Because modern day debate is overrun by trolls and teenagers, one cannot really debate them in any way which is usually done in serious debates, because they are not interested in debate, but just personal attacks.
And when Ad Hominem becomes a debating standard on some site, one must use different methods to counter it.
the best possible method is Machiavelli delayed response rule.
Simply, you:
One, make your argument
two, they respond with Ad hominem
three, you delay response.
Simply dont respond immediately. Let them wait for you to respond, or let them throw more Ad hominems while you say nothing.
the minimum waiting time to respond is usually 7 seconds after they are fully done responding, but a better way is to wait few minutes before giving another argument.
In fact, the ideal way is to just post argument, and when you see them responding with ad hominem, just dont respond at all, close app, and then open it again after five minutes, and post another argument while completely ignoring their personal attacks.
And doing this repeately exhausts them. Because if you post one argument every 5 minutes, and they respond with bunch of personal attacks each time, you are essentially forcing them to write much more than you do.
Because to each argument, they are forced to respond with 3 or more ad hominem replies.
Machiavelli way is simply, dont argue, make a claim, wait for them to respond, then delay your response for minutes before making another claim.
this forces only two possible outcomes: they either write more personal attacks each time, looking desperate and insane, or they stop with personal attacks.
But never respond with personal attacks to them, but force them to exhaust their personal attacks.