It hurts his draft rankings for sure, but for his development it is debatable. The lack of scouting exposure is no good. Some NHL teams don't even have a scout in Finland, never mind in Mestis, and then they lean on second-hand information, which makes much likely that those teams will fall in love with another player.
Based on what I saw in the last years under-18s championship, he should go in the early-to mid second round. If he goes past that, it will be a great steal for that team that picks him. The skill and puck handling is all there. It will be interesting to follow the draft.