TL;DR yeah I think you’re right. The original announcement from the Reddit admin comment didn’t give any details, so I filled in the gaps myself and assumed “heart” would imply compassion, especially since I’ve seen that “stay for the empathy” tagline for so long. After all, why would the change from “front page” be necessary if “heart” of the internet gives a the same sentiment that it’s the core or cutting edge?

The contracted marketing team’s writeup has some limited insight into the reasoning:

…Reddit’s updated brand materials would all point back to four traits: inherently eclectic, positively different, delightfully absurd, and genuinely candid. These traits, along with the uniquely empowering foundation of Reddit as the best place to discover and participate through real conversation, led the team to a new, strategic description of Reddit as “the heart of the internet.”

I’m not experienced enough in marketing jargon to understand if this is saying that “heart” only implies that there are lots of communities available on the platform, or if “genuine” and “real conversations” should be factored in to imply that these conversations and communities should be heartfelt.

But all in all, it seems like the focus is on “you can discuss with lots of communities.” And since “front page” doesn’t imply discussion as much as it implies reading a newspaper, the change was needed.