That Oly zoom is F8.0 equivalent. Now, I know M43rds doesn't like equivalence, because it punctures their world view. OUR lenses are small and tiny because we are mirrorless! We are cool, because we violate the rules of optics and light gathering. And let's ignore those pesky cell phone users, who also have F2.8 lenses.
Like removing the mirror makes lenses smaller.
The f-stop is the relationship between sensor size and lens size. That's it. A cell phone camera, M43rds, and medium format can all have F2.8 lenses, meaning the lens has some ratio to the system sensor size.
However, the medium format F2.8 lens performs far differently from a cell phone F2.8. Does anyone, can anyone, really believe differently? Does anyone really believe that the F10 Hubble telescope lens is worse than a F2.8 cell phone lens?
In their hearts, everyone believes and understands equivalence. They just choose to deny it when it comes to defending their system.
What I want is one, just one, M43rds user to state that a F2.8 cell phone lens performs the same as a F2.8 M43rds lens. And once you admit that, you might as well put interchangeable lenses on a cell phone. It would smaller, light, and cheaper. And offer the same performance, right? Then we could argue about why M43drds F2.8 lenses are dinosaurs and use such big and heavy lenses compared to cell phones
Funny though. No one has ever brought this argument up, even though it is the logical conclusion of "F2.8 is F2.8 is F2.8"
On the other hand: have you ever seen a FF 24-200 lens?
Now, SLR camera makers don't make F8.0 zooms, because they are too slow for normal use. Sure, they'd work fine outdoors in bright sunlight, but that's about it. The slowest SLR lens is maybe F2.8 equivalent, and that's a $200 kit lens.