Ah, I assumed you wanted to fix something that needed fixing.
If you are set on implementing a site to post gamedev classifieds, you'll be stuck trying to get users from the sites you mentioned, which already have this feature.
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If I do the exact same thing as these other sites, then yes. I was simply trying to get a feel for what is needed by developers in the industry. Marketing was just one of the many options I listed there. But there are many big name marketing platforms as well. I appreciate your opinion that marketing is a challenge as an indie dev and as one myself I agree. I was just stating how there are several big name, established sites that help promote/market your game already. But no matter how good the platform is, if you don't have a game that people want to play, it won't become successful.
If a platform could magically make anybody's game a hit, then anybody and everybody would be millionaires from making games.
And to follow up, I'm not saying that it can't be done. I 100% agree with you that marketing an indie game is frustrating. There are definitely some great games that go unnoticed. I was just saying there are only so many tools a platform can give you to become noticed and existing platforms provide most of these tools. The rest is on you to stand out.