Yes, that is literally what it was designed for, and the only thing it was useful for.
It’s now, I suppose, useful for identifying people to avoid, but it’s no longer useful for preventing impersonation.
That's exactly why it was useful. Major institutions and public figures have impersonators, some satirical and others intentionally misleading. The check made it easy to sift what actually came from someone and what was either lies or satire.
On that front it hasn't gotten too bad because the grey and gold checkmarks exist.
Now blue checkmarks are a sign to ignore the tweet because it's someone who's just paid to boost their signal. Of course this has rendered the thread of replies to a given tweet unusable since the top posts are all posts by people who have paid to be seen rather than posts with more likes or retweets (actual signals of value/popularity).