While it is true that you were getting more likes and interactions when you were sharing yours posts on discord, I don't know if we can call that advertising. You were sharing a Hive post about Splinterlands on the Splinterlands discord, so you're not reaching any potential new players. At best, you're getting eyes from people who don't use Hive much but they already play Splinterlands.

The only upside is that with so many likes the posts might have been trending, reaching people outside the Splinterlands community, but still inside Hive. I don't know if there are any people already on Hive that haven't heard about Splinterlands. Even if they get curious, a post about Survival Mode is probably not the best introduction for a new player. In that spirit, bravetofu's post with his offer for new players signing up under him is more relevant.

Regarding the spam aspect, you have to understand that if every person shared all their posts on discord, it would get crazy. Should they make an exception for you? There is a channel for sharing posts but no one checks it. Maybe you could PM someone on discord to ask for permission to share a post. Even that might not be great as it could create a lot of spam for those validating posts.

Your posts didn't die. I've been posting regularly for more than 2 years and I don't think I have ever gotten 700 likes.