Most of the memecoins are made to scam people. Quick pump and dump scheme. People invest in those coins with the hope of getting rich. But only few lucky ones that act quick make some profit, while rest of them loses everything. None of those meme coins survives long enough. They all eventually die. Dogecoin has no real use case, but it was the first meme coin and so it has a huge advantage along with a strong community support. Shiba is also another meme coin, but they also have a huge community and actively wants to develop it and bring actual use cases.
Those coin keep on showing up because it is a decentralized market and no one can stop them from making a new coin.
Meme coins and shitcoins can be an equivalent to pyramid scheme/scams because only early investors gets the benefits the most. Early investors must also invite people in the form of shilling the coin so that more people joins and more money for them and for the developers of the coin.
This is can be their true purpose on why they are created because they don't have other real use cases anyway however there are coins with a unique technology around them but the only problem is they join the hype of the meme trend where they also use a name of an animal, this makes them mistaken as a meme coin and legit investors will avoid them.