You simply need to install a PubSub client library in your Arduino IDE. The most popular one is this:
If you’re looking at using MQTT then you might want to consider a slightly different approach with Blynk, which is to use Node-Red and the Blynk plug-in. More info here:
As to why there are no pre-built binaries for Blynk, I guess it would be possible to do that, but it would need a very specific set of hardware, and it would need to have Wi-Fi provisioning built-in to allow that hardware to connect to the local network and use the appropriate Blynk auth code.
Much better to have the Sketch Builder to generate your code for you:
Pete.