the purpose of using TAP is to be able to write IP stack in user mode code; however TAP is not the only way on linux, you could also use raw(AF_PACKET)or XDP so

the purpose of using TAP is to be able to write IP stack in user mode code; however TAP is not the only way on linux, you could also use raw(AF_PACKET)or XDP socket, they also allow you bypass kernel IP stack