Indeed not. My 16" incher has been all over the Scottish countryside without issue.

I'm really starting to think that all this frame material / wheel size / saddle type & position / IGH vs derailer / etc. stuff is only relevant when you get to the last 10 % of the cycling experience. As long as the bike is comfy, safe, doesn't break down every 15 miles, and the rider likes it you're 90% there.

I can't remember the last time I rode a bike (in good mechanical condition) that I didn't like.

I guess with folders making sure it folds small enough for your needs is essential too.

The last 10% can't really be decided until you've been around the block enough times to know what you really want, and is entirely individual.