In case this article didn't make it clear, the purpose of the funnel is to divide up your customer flow into measurable areas. It's okay to make a funnel with two or seven stages so long as you can measure each distinctly, and it is useful to troubleshoot your marketing. (Although using industry standard terminology is helpful).
I love this focus on the funnel.
Yes, a "funnel" isn't a completely accurate representation of how people buy. All models are wrong, some are more helpful than others, and this one remains helpful.