The fact is you overlooked to configure your Tasmotized devices, like it’s described in Tasmota’s own documentation for its MQTT feature.
Respectfully, I wish I had a dollar for every time someone used their work background as a defense for their mistakes. I also found I had a lot to learn but didn’t blame the documentation for my errors and attributed it to, me.
Here’s the very first line (emphasis mine):
This integration allows you to control Tasmota devices over MQTT.
It’s pretty clear the Tasmota devices must communicate via MQTT and they certainly won’t if their MQTT settings aren’t configured.
FWIW, prior to the introduction of the Tasmota integration (very recently), Tasmota devices were discovered via Home Assistant’s MQTT Discovery (it can still be done but the Tasmota project is phasing out support for MQTT Discovery in favor of their own technique). Anyway, the upshot is that for years there was no documentation in Home Assistant for specifically discovering Tasmota devices (or any others). All of it was (and still is) done by configuring the Tasmota device as per its documentation.
Nonetheless, if you feel the documentation should read like a tutorial, then the good news is that anyone can submit changes; you are free to enhance it to the degree you believe is necessary. Someone on the development team will vet your submission and, if approved, it’ll be incorporated into the official documentation. If you want to learn how, here’s a Community Guide: Editing the Documentation and Creating a Pull Request on GitHub
BTW, the custom of this community is to add the Solution tag to the post that introduces the idea/instructions/concept that resolves the original question/problem. You have chosen to mark your own post which simply repeats what was already suggested by others. If everyone did that, it would appear that all users ultimately “solve” their own problem. In this case, sheminaslam was the first to identify that you overlooked to configure MQTT in Tasmota and so that’s the post that ought to be marked with the Solution tag.