I think there are two sides to this coin.

I think a lot of pro-Trumpers like to give this advice to ignore Trump's tweets. I think their advice is not to sincerely help the Democrats, surprise surprise. To wit, if we get into a habit of ignoring Trump's tweets it, many will tend to forget just how terrible a person this is in the White House.

Forgetting his character means a few things - Trump supporters will no longer have to defend the terrible stuff, either to friends or too themselves; Trump supporters are less likely to worry about what people who do not talk politics with them think about them; and in my opinion, Trump is more likely to be re-elected.

For my part, Trump either will or will not be re-elected. I just think daylight is the best antiseptic in any event. I'd rather have Trump be re-elected with everyone knowing just how terrible a person he is than (in your theory) have a slightly better chance of beating him while giving all of his supporters soft cover. It's useful in business and personal interactions to know who will support him with full knowledge of his words and actions.
It's like playing golf with people. You learn something about their character.