This argument seems shallow because the author already clearly and specifically argued that the growth in cost is not proportional to the growth in services authored. For example, one of the first arguments put forth by the author is that bandwidth costs have increased by about 11x, expenses increased by over 1,000. Even straightforward commodity expenses such as hosting costs have increased more than expected, 33x.
So while yes your argument is true that in fact the platform is growing, that however as an argument hete isn't really demonstrontative of a correct understanding of the problem the author argues.
TBH, that 3x increase in expected hosting cost (33/11) doesn't seem bad to me. Maybe Wikipedia has a lot more redundancy now, maybe their pages load faster in more countries, maybe they're using external cloud providers instead of running bare metal, maybe they host more stuff that doesn't get as many page views, etc. (For example, I'm pretty sure I could host HN off my desktop computer, but I'm sure it's hosted in a safer way than that.)
How many employees is the right number? Is "1" the right number, is "300" the right number? How does Wikipedia's growth compare to other well-known companies?
So while yes your argument is true that in fact the platform is growing, that however as an argument hete isn't really demonstrontative of a correct understanding of the problem the author argues.