Actual quote from the article for context:

> Modeless: Computer scientists when writing code typically worked in different modes; you might have an insert mode, a delete mode, or a replace mode. You would first select the mode, then select the point on the screen at which the action was to occur, then perform the action. Tesler, in user experiments, proved that modes were confusing for nonscientific users and championed the “modeless” interface.

For non-technical users, sure modeless editing may be better. But for computer scientists, modeful editing may be better. The article mentions modeless editing to be better for no scientific users only, not necessarily for everyone.