Deplatforming might, but the very fact that you're confusing deplatforming with "not amplifiying" really illustrates my point re: people thinking unless an opinion is being actively amplified, it's being "suppressed".
I'm not suggesting deplatforming. I'm suggesting we stop promoting opinions based on algorithms and metrics on social media, particularly where opinions are promoted because they "increase engagement" (which usually means they're extreme and/or controversial - reasonable opinions tend not to "increase engagement"). Even if you just made it so stuff only went to people if people manually sent it to them (effectively putting their name on it) you'd potentially make a huge impact.
(Re: the SPLC in particular there's no question deplatforming makes their job - tracking extremists and extreme groups - harder, because it means those people are no longer happily outing themselves on social media.)