The tablets have nothing fancy in them other than some dyes, they are just soap at a mark-up. Even the cheapy store brand stuff does just as good of a job.

Additionally, depending on the hardness of your water you may need less detergent than the tablets have in them which could leave a white residue on your dishes.

Finally, with the powdered detergent you may need to sprinkle a little in the door for a pre-rinse which you can't due with the pods. Check your washer instructions.

P.S. Never use liquid detergents.