Its not the only thing that matters. The 1 5-on-5 point matters. The fact that he showed he can function in the NHL outside of 5 on 5 play matters. The defensive issues matter. The times he looked lost out there matter.
The thing that matters the most though is his age.
Outside of his special team stats (which slowed down considerably), he hasn't been doing well. That's quite okay too, dude is 19.
Philly needs to build a team still, Michkov's struggles might be a positive for them. It shows that they have time to be patient.
The 1 5 on 5 point is a convenient narrative that easily falls apart when you ask how many even strength points he has. When you have to go the lengths to split hairs between even strength and 5 on 5, you have a narrative with holes in it.
Yes, a 19 year old small winger is better when he has more space? This is not a big deal, and is pretty obvious. I think anyone should've expected it. His 5 on 5 numbers are also a product of his team, and actually they are pretty decent compared to the rest of his team, last I checked. If he was playing for Florida or Dallas, I think his 5 on 5 point totals would be very respectable. Hard when you are playing for quite literally like the worst team in the league.
And his special teams stats haven't slowed down. He had a point the game prior to getting scratched on the PP. He had a few games where he didn't pick up a point. A few of them he played well. There were games where he played poorly and got a point. This is called a small sample. 10 points in 13 games is the player he is. That's over a larger sample. Making a lot over a few games trend here or there for any player is not recommended.