i dont really agree with this either...and thats comming from a freemium
I have 2 accounts , 1 with camilla , tethis , cellia and the rest are pretty much event units. WHile i do have 1 of the better healers and 2 good duelists , this accounts pales in comparison with my second which has nanaly , jerome , uzume , lyla. Just getting 1 black can make1 account that much better.
Nanaly literally solo carried my second account (which was like 70 - 80 levels behind my main one) for the first events - started playing again 3 weeks before oddettes event - and the only event that i didnt managed to 3 star was solanos....and that was because i was unable to 3 star the last map
Getting a couple of very usefull plats (like jerome and uzume) was also great , and made me able to pass war of magic easier , without belinda for example , and without having to awaken or cr yuyu or multiple silver witches (at this moment i still dont have any cr caliopee on either account)
Getting a monica also made my second acount farm dcs quite a bit better (considering that right now my second account has more dcs and more awakened units then my main)
In conclusion , premium units an be really powerful to have...but they are a risk to aquire. Most of the times , the risk aint worth the cost , i an agree with that , but the rewards can be great as well