When I started my career, my mentor was an emacs user, and the reason I started with emacs. I became very proficient with the editor, learning how to handle multiple buffers, window splits, rectangle selects, etc. At that time, I didn’t know vi. Until I started working on another project, where the project manager made a statement to me that started my migration to vim. I was logged into a machine that didn’t have emacs, and I was complaining about it. “Just use vi”, he said. “I don’t know vi”, I said. Then came the statement that stuck with me, “Son, you got to know vi just enough so you don’t look stupid.”
So I learned vi, just enough to not look stupid, and eventually, as proficiency set in, turned to vi more often than emacs.
Now vim is my primary editor, and I can use emacs just enough to not look stupid. ;)
Back to defaults. I customize my vim with colorized syntax highlighting, and several plugins. But at its core my vim is still default with respect to key bindings. These are the defaults that matter. If you leave key bindings alone, then the core of vim use is identical anywhere you use vim, with or without your personal vimrc. You can a make “stick to the core defaults” argument for just about any editor. Just keep the core defaults, and customize away on systems you use daily. Then when you use the editor without your personalizations, the editor still behaves as usual.
My editor life is also easy, but with some more creature comforts for daily use.