Did Spotlight break in Big Sur(ly)?
I’ve stopped using it because I can never get it to find what I want.
I have had to resort to dropping to digging up a tutorial on the Unix “find” command(of course I can’t remember how to use find) , then drop to Bash and look for files that way.
Can Spotlight find filenames only, without looking at the contents of a file? I rarely need to search for file contents, although I can see how that is useful at times.
Spotlight has long supported search prefixes, so name:happyPiglet will return files with the term as a substring in the name.
However, could things be broken in Big Sur? Possibly. 
Outside of needing to reboot my M1 Air, a name: search worked just fine.
Do note: It is still indexing at the moment which would logically affect the results.
For finding files? Why?
I suppose that’s subjective. 
As @DEVONtech_Jim pointed out, you need to use the “name:” qualifier to find the files, but even then if you click one of the results Spotlight wants to open the file, which isn’t what you want. I think what you want to use is Finder Search instead of Spotlight. From there, you can choose “Open in enclosing folder” etc.
Indeed! Good ol’ Command-F in a Finder window works a treat too. 
I’m just going to echo the Alfred recommendations. And I say that as someone who took almost a decade to start using Alfred. I’d heard recommendations, I even played with Alfred a bit, but I never got into it, until this single comment from someone piqued my interest enough to look at it more clsoely.
Alfred is faster than Spotlight. Even though Spotlight is built-in.
That proved true. The commands are simple-as too, in Alfred, for what you requested.
“john” - Will search for app names containing the word John
" john" - With the space at the beginning, will search for file names containing John
“in john” - Will search for files containing the text John
However, clicking a match will cause the file to open, which OP doesn’t want.
It’s command-click (or command-enter) in Alfred to reveal in finder for me.
When I need to search my entire Mac or even some out of the way corner, I open the HoudahSpot app, which uses the Spotlight indexes but gives me a more flexible, guided, front-end without having to remember search syntax.
I love HoudaSpot and use it regularly, but for me it is the nuclear option when it comes to search. Unless I know I need the advanced features I’ll usually try Alfred first. If it comes up empty then I’ll fire up HoudaSpot.
Because I need the files, and don’t remember where they are.
I’ve had a license for Alfred for a long time but never got around to learning it. It sounds like overkill if spotlight can search for files though.
One of these days I need to take Alfred 101
Will finder search the whole file system or just the current directory?
I never knew this- thanks
Why use a launcher when I can launch spotlight with a keystroke ?
Indeed:
Also a recent episode of Automators:
I’ve tried Alfred, but I still love Launchbar more.
Right, and not only that, but Alfred has a lovely usability enhancement where simply pressing down Cmd will put “Reveal file in Finder” underneath the highlighted result. Or, pressing Opt will put “Search for ‘term’ in Spotlight”. Or, pressing Ctrl will put “Search for ‘term’ with default fallback”. So basically, you don’t even need conscious effort to memorize the modifiers; you can just press them and it will tell you what happens until you naturally memorize them.
I definitely recommend Alfred, for all the reasons people mentioned.
If you want a better tool for finding files by name than Spotlight, there’s also EasyFind, a free app from DEVONtechnologies (makers of DevonThink, obviously).
