And 20 dollar would not be worth the work even with bots for richer countries unless they sold a very high volume.
When you look at average monthly incom on poorer countries however even one account a month is quite substansial!
Madagasker (33 USD), Congo (36 USD), Afghanistan (48 USD), Ethiopia (55 USD) and Nepal (61 USD) is just some examples. (Taken from worlddata.)
People who create accounts on bitcointalk and rank up have basic computer literacy, access to a computer/smartphone and the internet. This would put them in the very top of the population of third world countries. Their time could definitely be put to better use.