CoD does have that problem and weakness, sure. I would argue that you should toss Languages into "Academics," as Supernatural Lore gets tossed into "Occult," but I digress.
I did not explain what I meant by "mechanical growth." By that, I mean "an increase in total XP spent on the PC." I omitted that when I jumped to my argument that there should be mechanisms for "mechanical change," such as a re-spec. So, in response to your bullshit claim, I'd amend my statement to: no form of role-playing requires an increase in total XP spent on the PC.
Of all of my previous reasons for wanting to cap growth, I strongly lean on the idea that PCs should not be able to effectively eliminate all of their weaknesses, which is what unlimited growth permits. If a PC at the limit learns a new language, then they should be able to shift their expenditures to permit that change. Of course, the change means that the PC sacrifices some other ability or merit, but that's not unreasonable, e.g., I probably used to have Athletics 2, but, thanks to age and lack of practice, that's probably down to a 1.