Why no Olympus "pro" standard zoom

Domagoj Batinic wrote:

there is no 70-250 in 4/3 , you have 70-300 or 90-250

i've tried 70-300 on E-M5 and it works fine, it never was a fast focusing lens so on E-M5 slower focusing of 4/3 lenses is not really noticeable with this lens. and it's not unbalanced combo

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my gear:
E-M5+45mm/1.8
E-520+12-60+14-42+70-300+Sigma 105 + FL-50R+EC20 + SRF-11
and good number of legacy lenses (list in profile)