That's not the same as "terrible" though? Signal is basically "whatsapp but not facebook", but you wouldn't say it's "terrible". Same with lyft (which came after uber), or ubereats (which came after many food delivery startups).
Every online gaming platform other than Steam and GOG sucks. And in fact GOG competes very well with Steam precisely because it offers something Steam doesn't, which is DRM-free games. Steam didn't just beat the Epic Games Store and Origin and Games For Windows Live because it came first, it's just a better platform and the others offer nothing outside of exclusives which they paid for.
I'd personally say it was better as a launcher. Launching Steam itself takes relatively long and when its just in the background its just there idling with ~400Mb of RAM (specifically its WebHelper), which aren't a problem with Battle.net since it idles at 170MB or you can just close it since it launches way faster.