The data is not the only thing which needs to be transferred.
WiFi systems "talk" to each other and then negotiate the data transfers. The data stream will be interrupted periodically for more "talk", then resume again.
Imagine being at a blackjack dealers table. The cards are data. How can you get the dealer to give you data? What happens when you want the data flow to stop? What do you do to get more data? What do you do when you have all the data you need? What would the dealer do if you didn't put your bet down at the start of the next hand?

Lots of decisions to make that have nothing to do with data.

Different encoding schemes? Imagine the different people at the table speak different languages. What must the dealer do to communicate with all those different people?

 

It seems modulation encoding would be as simple as "this phase represents 00, this phase represents 01..." Why does there have to be complicated encoding schemes for wireless digital transmission?

The answer to most of your questions come down to efficient use of bandwith, noise immunity, and reliable data recovery. As I said before you will need to acquire a considerable amount of background information in order to appreciate the benefits of the techniques you are asking about. A thread on a hobbyist forum is not the place to acquire this information.

 

jaydnul.......one of the first digital encoding schemes was the Morse Code. And the first digital modulation mode was OOK. On-Off-Keying. Turning the carrier on was a mark...or a one.....and turning the carrier off....was a space or a zero. CW transmission.

Then came AM, FM, and PM. With these...we used two tones...one for mark and one for space.

It was discovered that when we used OOK, AM, FM, or PM..........turning on and off, or switching tones.....caused sidebands to form. In other words....modulation cause the signal to spread out and take up a band of frequencies....not just the carrier. The faster the data.......the wider the bandwidth got.

This is very limiting with large amounts of data......like a video signal. With the digital revolution.....we are able to combine AM, FM, PM......to increase the amount of data within the bandpass. With OOK, AM, FM, and PM the data is sent bit by bit serially. With QAM, we can simulate sending words....not just bits. Sorta like the difference between a serial and a parallel bus.

Does any of this make any sense?