That may very well be, but I sometimes find the process of insisting upon a 'proper' finger legato creates more issues than it solves, especially when substitutions have to be made that create a break in the physical continuity of a phrase.
If finger substitutions create a break in the physical continuity of a phrase, I'd say you are doing something wrong. You constantly need subtitutions in Bach, Franck, Chopin etc etc, all composers who require very good legato and long lines. Assuming the goal is an as strong a legato as possible, I'd rank from easiest to hardest in achieving this
1. Legato fingering
2. Legato fingering with substitutions when needed
3. Non legato fingering with pedal to cover up the holes
Being in continuous physical contact with the instrument is in my opinion the easiest way to play legato. However, if you do finger legato poorly, no amount of pedal is going to be able to hide that your legato is lacking, even if the notes are physically bound to each other. Legato is more than just one note sounding until the next one sounds.