Edited for grammar.
I think what he means is that the title is excessively general "Why it's hard to love Google Plus in Africa". It's a bit like writing about the trouble you are having getting a fast Internet connection in Guatemala and then saying "North America" has connectivity issues. Different countries in Africa are very different from each other. It's like generalizing across Cambodia and Japan because they are on the same continent. Big difference...
I was just a bit confused by the parent post's reference to South Africa, which was a bit off-topic as the author is from Zimbabwe. My assumption was that there were two possible explanations, that the post's author confused South Africa with Southern Africa, or that they considered South Africa to be so much of an outlier in this regard (which it isn't) that the submissions from South Africans weren't relevant. Either explanation would be wrong and worth correcting.
Indeed Zimbabwe is not representative of all Africa. However, Zimbabwe actually has better internet that most African countries. At least it's in the top 10 of 54 countries on the continent according to Ookla (http://www.netindex.com/download/allcountries/)
If Zimbabwe's internet is bad enough to cause users problems loading Google+, It's likely worse in the majority of the countries on the continent.
Generalising therefore was not meant to paint the picture that all Africa is the same, but that Google (if they read this) need to have a strategy that takes into account the poor internet quality the bulk of Africa has.
I do understand the point you were making, but unfortunately it does create the potential for your point to be forgotten as the discussion gets derailed into what is and what isn't representative of Africa. It may have been better to make that part of your title the 'Developing World' or something similar.
In any case I agree with the point you were making, which is that too many sites, especially social networking sites, are paying too little attention to optimising the experience for those on slower connections with high latency. So kudos for raising it and pointing to a specific example (Google+).
There's really good map of planned and existing submarine cables to Africa at http://manypossibilities.net/african-undersea-cables/ which gives a fairly good idea of where the best and worst internet in Africa is
These terms are just descriptions, there are no hard, objective, definitive rules about it.