> Salesforce acquired them and just let it die, baffling.

This is a common misconception, but it's actually not true. The reality is even more bizarre.

Most of Heroku's successful years came after the acquisition, not before. Heroku was acquired extremely early in its lifecycle, and Salesforce does actually bear responsibility for investing in it and making it the powerhouse it became. Most of what people remember as the glory days of Heroku came long after the acquisition. And in fact, at the time of acquisiton, Heroku was nowhere near as competitive as a product as it later became.

It was only much later on that Salesforce began to pull the supports out from underneath it, leaving it to fall behind and become what it is today.

The narrative of "BigCo™ acquires startup, then leaves it to wither and die" is a trope because it is very commonly true, but it's actually not what happened in this particular case.