There is absolutely no reason you can't use liquid ferts for daily WCs. There are plenty of dosing methods that are done this way. You just have to adjust your dosing for the amount of water being removed. It's basic math. BTW root tabs alone are extremely limited. They will only really feed plants within a certain distance and that are obviously planted in the substrate. Which would eliminate moss, anubias, ferns, etc.
I've only had the discus for a relatively short while but I resumed dosing after day 4. I dropped the dose by 50-70% depending on what the plants look like but I'm still using ferts. I plan to drop a lot of vall in the tank to cover up my black background and also to get a fast growing plant that will feast on the nitrates. They can get excessive when you go from feeding your planted tank once a day to a planted tank that requires 3-5X.
I'm also still using pressurized CO2 but that's another discussion.