IE based games are not RTwP, it's "fast forward turn based with pause".
Evidence is whenever you engage battle,
1.there are rolls to determine who can initiate action/attack first
2.you can "buffer" command to cast before it's your party member's turn to cast
3.AoE spells are rolled against each target in range in turns
4.You can cancel action and change to another if it's not your turn yet.
5.The matter that you can set the setting to pause when battle starts.
By realtime, which means there will always be cool down, which IE based game doesn't have. In IE based games you can't cast spell one after another "if" it's not your turn yet, they get buffered in queue. Even moves are pseudo to pretend it's realtime when it's not. ie. you can still move while enemy attack animation is on-going, the damage is based on result of roll, even if you are a few step away you still receive damage anyway.( There are no "mana" point either, you get only specific amount of charges, and must rest to regain charges after battle.)
That's why they said it's "modified DnD ver.X rules", because on table top you can't move until it's your turn. If you have no instruction before turn ends, it's essentially give up your priority. If the entire turn is not finished yet, you can still do things. It's all in the combat logs.(If you turn on those dice roll messages.)
Hm, but that's just your own type of "definition". Let's keep it simple. There are two "main" types, real time and turn-based. It's clear that there are many different ways to implement a real time game, there is not only one way. The possiblities range from fast paced hack'n'slay to very low paced "pause based" real time combat like in the IE games. Cool-down ablities and stacking of spells/attacks is not a basic requirement of real time combat games, these elements are only attemps to minimize the micromanagement while pausing. In many ways the old IE games felt like some sort of turn-based game because you had(?) to pause often and therefore you could really play it like some sort of turn-based game in which you choose the end of turn by yourself (when pausing the game). But, yes indeed, the IE games had the DnD mechanics and it's inner turn-based time system but that's not the same thing as a turn-based combat system in which the player is forced to very specific and mechanical turns and attack orders (based on initiative) and things like that. In real time party games you could choose yourself which of your characters you want to give which order in the sequence you like. And in the end everyone will perform the orders simultanously and not "turn-by-turn".
So the IE games ARE real time combat games because orders are not performed turn-by-turn and person-after-person but simultanously. You cannot argue against it. But yes, you can give the games some sort of "turn-based feeling" by using the puase funcionality often and regularly which is almost a requirement in high difficulty settings.
Imo the range of real time designs is much bigger than the very specific turn-based system. But you can still create very good games with both systms, especially for parties (since turn-based is quite senseless without a party).
