I agree that this is a kind of a personal issue - to use a file manager or not in Linux, but I heard that it's also a bad practice to use a file manager especially for newbies because first of all they have to learn the shell and all file manipulations should be done from the shell. Is that true and do Linux users use file managers?
Everyone uses what one finds best for a given task. This is almost completely individual, there cannot be a general answer.
Linux users do not need to learn shell operations at all if they don't feel like (and don't get forced to by some situation). And the other way around: one can perform all the needed tasks using only the command line (no file managers or GUIs even). It all depends on what you (intend to) use your system for.
I use a file manager quite rarely. When I went from Windows to OpenBSD I tried to learn "the unix way" so I got very familiar with the shell and such. Now however I've came to realize that shells are very handy, but in some cases they can't beat graphical file managers.
I use a graphical file manager when:
- Dealing with long or "difficult"(spaces, etc) named files where I just want to select a few files and copy them or do some other simple operation on them.
- Mass file renaming that can't be automated in any foreseeable way
- Dealing with pictures (seeing preview tiles is very handy)
Other times I use a shell because in general, I can get things done faster.
Necessity. Today's users have hundreds of thousands of files and terabytes of storage. Tomorrow's users will have even more. (Check the graphs for storage density over time; it's logarithmic growth.) A good 'Finder' is more necessary now than it has ever been; and 'Desktop Search' is also very important since 'Finding' is a task better given to the computer itself.