I cannot say what the industry standard answer might be, but I recently build a desk from 100% pine. I'm unsure of the species as I purchased "appearance boards" at Home Depot, but in SouthWest PA that's most likely Eastern White Pine, which has an incredibly low janka hardness (around 400). The desk top was finished with 7 coats of EM-6000 post-catalyzed acrylic lacquer and rubbed to a perfect gloss. You didn't mention any coating or finishing method, but I'll assume you'll be using some form of lacquer or poly.
I have been using the desk for just over a month. It has several computer speakers and a 30+ lbs 30" monitor sitting on it. I constantly set my phone, stylus, and bluetooth headset down and pick them up many times each day. I have had hot tea a handful of times. I'm not rough when placing items on my desk, but I'm also not overly gentle.
So far I have no dents, no nicks, and no easily visible scratches. With a flashlight I can find a few scratches when lighted just right, but those are definitely in the finish and not the wood. There is zero deformation under the monitor, which has been in place continually.
So from experience I would say almost any wood has sufficient hardness to act as a common desk if properly coated, assuming there are no unusual uses for it. Scratch resistance of the coating is going to be a more serious concern, especially if hard items like keys are constantly dropped on it. A poly-urethane is probably a better choice than lacquer, but the lacquer gives such an incredibly deep gloss that I couldn't bare to use anything else myself. As long as you're finishing the desk top, any wood should be fine.
Update: After over four months of continuous use I stand by this answer. I recently moved everything off of this desk including my monitor, so that a group of five could play AD&D. There was a lot of books, constant writing with pens and pencils, leaning by players, cups and glasses of various drinks, and much much rolling of hard dice across the bare lacquer. I see no deformation from the monitor, books, or leaning, no surface degradation in the wood, and just a few light scratches in the lacquer (I can count them on one hand). There is a dent in one corner, in the one area that I did not coat properly with the lacquer, and all coated corners (which are in more heavily used areas) show no wear at all, supporting my comment above about making sure you use the right finish for the job.