Replace software with retail in your example, it doesn't sound so abnormal
"Walmart can, at will, remove your entire line of potato chips from your (their) customers and your existance in their stores is just gone."
The store analogy also has very limited switching costs, for example if Walmart stops selling brand X of potato chips, it's inconvenient but not impractical to go out of one's way to buy them at Target. It would be different if buying potato chips at Target would involve throwing out everything one has bought at Walmart and buying the same Target-equivalent merchandise (ie. switching from iPhone to Android, one would need to buy equivalent apps).
Epic's problem is that they want a Epic Store on other people's devices.
If you include using 3rd party apps like AltStore, then yes it meets a reasonable definition of convenient, imho.
No! You need to move away from Walmart.