Perhaps that may be statistically true for the majority. But that doesn't rule out individual exceptions, especially if you go out and make them for yourself.
I came out at nearly 46, and my late 40s and early 50s were the most sexually successful and active of my entire life. Over the past 17 years I've had 2 BFs of over 2 years each, a number of shorter relationships, and 2 partners in my 50s (2 because the first one died not long after we got together).
At 46 I realized the great disadvantages I faced: from age, particularly in the gay community, from lack of experience in this new life I was attempting, and from other drawbacks like indifferent looks and little wealth & possessions to attract guys.
I also estimated that I had at best 10 years before my looks and vigor were totally gone, based on family history. Added to that was my profound anger at myself for having wasted 30 years of my life in mistakenly pursuing a straight existence.
So I determined to learn everything I could about the gay life, and to make being gay a full-time occupation, to try to squeeze 40 years into 10 by age 56. And fortunately I was already retired with an abundance of free time, only doing such things as I wished for a little extra income now and then.
By focusing most of my time & energy on this task I increased my odds over guys of similar age. Plus I did get a break, finding a partner again at age 58, 2 years past the cut-off point I thought I'd have. But even greater marks to him, since he's older than me, his own feat that much more noteworthy.
So I wouldn't write yourself or other older guys off completely, if you direct your energies to the job. I think there's always a point to seeking out a partner if you want one, not only as a positive means to achieve that goal, but also in the enjoyment of pursuing it, or at least it's been for me. Because if I hadn't succeeded after all, well, I still had the fun of trying, rather than throwing in the towel and doing nothing.