Doge may have promoted bitcoin a bit as a meme(being a crypto-currency), other than that I don't think LTC or any other shitcoins actually influence bitcoin in any(positive) way.
I have to agree with you.
I know a lot of people who got started in crypto by using Doge as a joke first. They now use Bitcoin all the time. Doge has helped Bitcoin a lot. Although, Litecoin did help Bitcoin, because Dogecoin was based off of Litecoin, no Litecoin means no Dogecoin, no Dogecoin means less Bitcoin users. All the other shitcoins are only here for some people to make money.