Because I find it faster to switch by just spotlight + app name, in many cases even faster than command + tab, because it's kind of an O(1) switch, vs an O(n) switch to cycle through many open apps.
This is also the reason why both mouse-clicking and touch-tapping are slow compared to keyboard typing: you likewise need to look at what is where on the screen, then aim with the mouse or the thumb, instead of just jerking the fingers to keys that are in muscle memory.
To make things worse, I tried switching back to Alfred but it it seems to just piggyback off spotlight for finding apps.
Otherwise I would switch back to Alfred if it just had a “my index doesn’t get corrupted like spotlight” as a feature.
Otherwise, apps can conceivably be added as keywords or something. Rather annoying since it won't pick up new apps automatically, but oh well. Myself, I prefer Alfred anyway since Spotlight doesn't do too much aside from launching apps, converting currencies and occasionally looking for files (the latter is not so useful when there are thousands of third-party code files on the machine, and Finder is not my IDE anyway).
P.S. Also btw, at least with Alfred, I don't need even a full word for most apps—just two to four letters: i.e. ‘fi’ is Firefox, and ‘do’ is Double Commander. Alfred quickly ranks results higher if they were invoked previously for the same input, so the desired app pops up in the results just after a few letters, and this behavior sticks around without perturbation from re-indexing. This also means that at first it pays to enter those couple letters and select the app with the arrow keys, since Alfred distinguishes between inputs of various length—i.e. might learn for ‘firefox’ but not for ‘fi’.