I'd like to point out that you're trying to execute a rhetorical slight of hand that diverts attention away from the issue.

Harassment is real. This isn't about hurt feelings. This is about concerted attempts to ruin ppl's lives. Kathy Sierra's case for example included lies being spread about how she was an actual prostitute (not as an insult).

Should trolls be allowed to spread lies about other people?

Sure, Sierra legally probably was entitled to sue these trolls, but now it's on Kathy to expend her time, effort & resources trying to identify the trolls to sue them. Even if it's legal, harassment can also be used as a DoS against the victim, which is frankly, still bullshit.