While I agree with everything that Allchin says about the scientific myths and how they originate, I do not see them as a big problem in classroom teaching.
As a school teacher, I know that the historical approach is rarely used to introduce a topic, because it's very time consuming. Therefore, references mostly remain mere explanations of why, say, the Mendelian laws are called Mendelian and not something else. In the classroom, historical references usually reduce to mentioning that the Mendelian laws are called thus, because there once was a a monk called Gregor Mendel, who did experiments on inheritance. That's it. We simply have no time for long and mythical narratives, when teaching pupils with an attention span of 10 minutes at max.
The situation was similar at the university. My teachers wouldn't engage in long narratives about the discovery of nucleophile substitution, for example, but simply explain the mechanism of nucleophile subsitution with minimal historical reference. I guess this is the standard way of teaching scientific stuff in most classrooms.
Therefore, I feel that Allchin addressed a slightly improper audience. My hunch is that myth-making is much more the deed of science journalists or scientists who, in their dotage, turn to making their own Whig retrospectives (reviews).
But maybe I'm wrong on this and Whig-historical science teaching is widespread in other classrooms.
All teachers are short of time? Yet, do you believe that some historical information is worthy of making time for? For instance, if you want some of your students to become researchers, don't you think that getting a feel of what a discovery is would help them?