I wondered whether the bicycle water bottle holder could really hold a heavy bottle as the bike vibrated, hit potholes, etc.

Just making something that looks the same does not mean it will perform the same.

For example, would the lemon juicer in the picture withstand the dishwasher for as long as the shop bought equivalent? If not, how many times would the printed version be replaced and at what cost?

I just don't yet buy, in the examples given, that the items are of equivalent performance, and that is if one were to generously say that they had equivalent aesthetic qualities.

3d printing will get there, but it's not there yet.