I don’t get it: if it could pass as a platform-acceptable app icon, what does “mediocre icon design” even matter?
What’s the downside of the “mediocrity” you’re referring to? Is it simply pixellated under a microscope, or is it an altogether ugly logo?
In other words, if a startup’s minimally viable app icon is pixellated, who cares!? If it’s an ugly logo that users will associate with the startup’s brand, then that’s a bigger deal.
A minimally viable app icon is just that: minimally viable. If a startup doesn’t have the chops to design a minimally viable icon (i.e. the ugly logo), then the output is not minimally viable: it’s sub-minimally viable, and they should hire a designer.