"Is it also true that without other certifications before my rhcsa ex200k, the certification will not be of value even if I have taken the exams? Or that red hat won't recognize it, since I didn't take the training with them?"
The answer to both of these questions is no, they aren't true.
First, the RHCSA (EX200) is the first exam - there a no others before it.
Second, if you pass the exam, you pass the exam. It doesn't matter how you studied for it. Now, it is true that you'll have an easier time passing it if you do use the Red Hat training.
Third, you may be confusion the RHCE with the RHCSA. In order to earn the RHCE, you must pass both the RHCSA and RHCE exams.