So this post is not about React? because captial R ...
To me it is unreadable, a real PITA to process such capitalised titles. Especially with English language, for it has very short words, hence capitals can harm the reading rhythm every 4 or 5 characters; and the same word can be a noun, an adjective or a verb depending on the context (and there is close to no context in a title).
None of the English newspapers I checked does it.
In the USA, Wall Street Journal, NY Times, do it; but USA Today, LA Times, Chicago Sun-Times, Denver Post, Chicago Tribune don't. Washington Post apparently does or did both.
None of the Australian newspapers I checked does it (and at first sight, most of them seem to fall in the following category...).
Tabloids either use one foot high full capital titles, or don't capitalise.
Not any French, Spanish, German use this capitalisation style either. Of course Germans do capitalise nouns, as they do in regular text.
So, it seems to be an American-only thing, and not even widespread there (for newspaper titles).
"As regards publication titles it is, however, a common typographic practice among both British and U.S. publishers to capitalise significant words (and in the United States, this is often applied to headings, too)"
As to readability: I think you should see title case as a way to make text more noticable without going for the nuclear option "ALL UPPERCASE". If you look at it that way, you will be happy whenever you see title case.
I don't know of any standards that call for normal sentence capitalization for titles, so I assume they must be in-house standards or some standard that is not common in my domain.