That's exactly what it is. Grixis Delver for the longest time actually played 4 Ancestral Vision in the side just so it could swap them 1 for 1 with Delver.

You can read AcademyRuins comment for a quote from someone who probably knows more than either of us on the archetype.

Even Ryan Overturf said:

Delver is so frequently discounted in Modern partly because players approach the deck trying to capitalize on the potential speed of early Delvers.

Just having Delver in your deck gives you the potential to run away with games, but playing spells that cater to Delver ends up pigeonholing you into a deck that can only win short games, whereas building the deck with hard answers enables you to compete in longer games.

This leads to the question of why to play Delver at all—the answer is that Grixis Control struggles against decks that are fast and resilient...Putting Delver in your deck ends up making you generally weaker in blue mirrors, though stronger almost everywhere else.

Or perhaps from Kevin Jones deck tech? https://youtu.be/miguohLj29o?t=90

It's a Snapcaster Mage deck, it just happens to have Delver of Secrets

There's nothing tempo-y about it. You're a midrange deck with a turn 1 threat and hardly any counterspells lately.