That's silly. While you can't directly monetize your Twitter account, it can expand or straight up create your reach which you can use as a funnel to whatever monetizable content you have. That probably makes it less valuable for Twitter Inc., but it sure is valuable for Twitter users.
As a recent example, think of Pieter Levels (@levelsio). You think he would've gotten $10k first day sales on his avatar AI project without his Twitter account's reach?