When you can get your music on iTunes, Amazon etc. and all the streaming platforms for $50 (CDBaby) there is no reason not to. I really don't understand the authors reasoning here. It seems to go against everything they said about making your music available legally because people will steal it otherwise. Why withhold from any platform?
Also the advice on recording yourself isn't great. Sure you can pick up a book or look on YouTube but recording and producing music well is difficult. Mixing is difficult, especially without high quality equipment. The only way to get good is through lots of experience I've found, there isn't a shortcut.
>> "Yes you will need some money for equipment"
You will need a lot of money for equipment if you want to sound good. I use an Apogee ONE (pretty basic I/O device/preamp) and that alone is £300. A Shure SM58 mic (for vocals) is £100. An AKG 451 for recording acoustic instruments is £300. All this not to mention the recording software, a decent computer, and your guitars, drums, etc.
If you record in a studio all this is provided (and they provide much higher quality stuff than you could ever afford). They also usually have an assortment of high quality musical equipment (amps, guitars etc.) which you are free to use.