Yeah, they definitely started by scraping. Apparently 500 of the 13,500 apps were submitted post-Pebble, and Rebble also apparently did a bunch of other upgrades over time.
But you're right that there's some hypocrisy here, given their roots, and they don't really acknowledge that.
I think the whole conversation shows how ridiculous it is to be worried so much about who's "scraping" what. The open web is designed to be public and permissive. If you don't want someone accessing "your" content, then don't serve it to the public. And if you do decide to serve to the public, don't complain when someone accesses that data in a way you don't like. The Internet would be so much better without all these people obsessed about how their bits were being accessed and about whether X counts as "scraping" or Y counts as "scraping." Good grief, people! Find something else to worry about.
Perhaps in general, but in this case it seems like they did have an agreement not to scrape, which overrides the general scrape-at-will ethos that you're describing.
But you're right that there's some hypocrisy here, given their roots, and they don't really acknowledge that.