The quantity is not the issue, but the quality is: the Windows Store is full of dross, from outdated and abandoned apps, to clones and useless junk – but the situation is improving almost monthly.
The biggest limitation is that it is restricted to using only apps downloaded from the Windows Store, of which there are about 700,000 available. In other words Windows 10 S is meant to be more secure, faster and have longer battery life, like-for-like on the same computer. Strictly speaking Windows 10 S is Windows 10 Pro but with some limitations that are designed to, in Microsoft’s words, “be streamlined for simplicity, security and speed”. No tradition Windows apps means the desktop isn’t littered with program icons unless you actively choose to put files and shortcuts there.