I am not a doctor nor am I a medical professional. Just so you don't misunderstand.
I wonder what context the "effectively infertile" part was placed. Mind you I think I would focus on the word effectively. What it SOUNDS like the meaning there is that if you are constanting ejactulating then you are effectively flushing out the sperm and not giving it a chance to build up (i.e. lower sperm count) which could render you (effectively) for all practicle purposes infertile. I think that if you are worried about your sperm count then you should see either your family doctor or better still, a urologist about your concern. I think the problem with frequent ejaculation is that it gives you no chance (time) to build up the sperm in your body so if you are trying to get pregnant therein lies the problem. Mind you, that's just my understanding. When my husband went in for his two sperm count/quality tests he was to refrain from sexual activity of any sort for 5-7days. This was to give him a chance to build up his sperm so that the doctors could have a good sample to analyze. I've never heard anything about frequent ejaculation leading to permanent infertility. If that were the case then I believe you would see a lot more men with infertility problems. I honestly believe that either this article is incorrect or your understanding of it is, although I'm sure that I could be mistaken.