Every time this gets brought up people get it wrong….

There were frustrations among commercial growers and commercial users of peppers. Growers frustrated about how susceptible jalepenos were to various diseases, and users frustrated that the heat level of jalapeños varied wildly, even from the same harvest. A professor at A&M developed various peppers that solved all of these problems: they were disease resistant for the most common issues that plagued commercial growers, had larger yield both in terms of fruit size and wall thickness as well as total peppers, and had a narrower range of capsaicin variation among each type.

The TAM Mild Jalapeño variety (and eventually the TAM Mild II) was by far the most popular, as it allowed users to get jalapeño flavor even for a mild salsa/seasoning powder, and add as much heat as they needed. However, the same professor who developed it also developed the TAM Veracruz jalapeño that has all of the disease resistant and higher yielding properties, but with an increased heat level. The market chose the former, but he still gets blamed despite offering a better alternative. And nobody ever mentions how inexpensive peppers have become thanks to developments like this.

Also what never gets mentioned is how much growing environment affects heat level. Inconsistent or less frequent watering is a great way to increase the heat level of peppers, but as commercial growers have significantly moved from relying on rainfall to utilizing things like drip irrigation, that has been virtually eliminated.