yeah, but thats just numbers, in a perfect world.
i dont get the 80cs by 10, its more like 60.
anyone that gets 80cs on any hero in 10 mins either has a 4k+ MMR or is facing up against trash.
takes closer to 8-10 minutes just to get the double midas online in the bush, pushing the radiance back to 20 minutes.

IF you're not ganged or pressured early.
had 3 games with bear, first game, I was pressured out the bush to go fight early without my items because the team couldnt keep up 4v5.
2nd game the enemy pudge and riki perma roamed the bush, killed me 3 times and generally had me terrified inside my own bush, by the time my radiance was online, it was useless.
3rd game no midas, fast radiance in time for the first major team fight and qrushed them.

20+ minutes of afk farming puts too much pressure on the team.

also, using midas on the bear only gives you the gold advantage, the XP bonus doesnt apply to your hero.
so the second one doesnt pay off as much.