This “solution” would preserve the worst characteristic of defenders (their tendency to exacerbate the imbalance of already super powered cards — e. g. Damien, Stefan, Luiza) while eliminating defenders’ positive contributions to the game (allowing creative but marginal and fragile combinations that require multiple units or special set up and preventing NG, ST, and SY from immediately poisoning every decent unit played).
In short, you would preserve the value of defender for the two factions most commonly seen as abusing their power, while rendering them useless for the four factions for which they presently open possible archetypes.