Not everybody thinks they need such security because it’s their home computer.
Enabling device encryption necessitates the backup of the encryption key (and backup of the data files); otherwise, you may lose all the contents when things go wrong (like the key disappears after an update). People who don’t understand the tech may not know where their backup keys are.
Windows Home encryption is a hassle since you don’t have finer-grain control over the encryption, unlike Bitlocker on Windows Pro. This is the lamest scheme for Windows. You only get practical basic security with Windows Pro.
Enabling system drive encryption may make your system backup/recovery harder or impossible in some configurations. Figuring this out may require some technical expertise.