If you get some token then you should check the project website to know what is the use of the token, most token in crypto is a utility token that are going to be used in the platform once it goes life so before the platform is ready then you can use it to trade. There's also token that pay dividend or to use the smartcontract like eth or neo.
People should really research the ERC-20 tokens project if they are planning to invest their money into it, as you pointed out, it is highly likely that the ERC-20 tokens are created for the purpose of using it on platforms made by the developers, and if the developers are not willing to put in any efforts or time to keep on updating his project constantly, I would advice investors to stay away from investing in that specific project.