So from what I am reading, you need to have a heavy investment in both necro and summon... The necro summon is higher level than the level 1 incarnate so I expect it to have have better base stats once buffed by summoner passives. But the necro summon is not too great without those summoner points.

It actually makes sense to me. It just means you need to throw a ton of points into necro and summoner to achieve said build. I am not sure how great it is compared to spending the same amount on other trees. For example, I am pretty sure the summons dont hold a candle to a rogue/marksman in either damage or survivability. And you certainly wont have the utility of a mage using 2 other elemental types. Though I can see this easily replacing a tank but how long will it take for a summoner to be viable as a tank replacement? I am not sure honestly.