It's not so much a circle as just a newly coined term for "agent":
user agent ~= browser
agent ~= microbrowser
The terms on the left seem more technical/archaic, those on the right seem more populist/accessible.
On the other hand, since this one blogger seems to be the inventor of the term "microbrowser", it's still going to be ambiguous: easily confused with potential alternative definitions such as "lightweight browser", "headless browser" (e.g. selenium webdriver), "browser with low market share", etc.
On the other hand, since this one blogger seems to be the inventor of the term "microbrowser", it's still going to be ambiguous: easily confused with potential alternative definitions such as "lightweight browser", "headless browser" (e.g. selenium webdriver), "browser with low market share", etc.