Why do you say "Yes, not only to his apostles, but to any who were, or wanted to be, a disciple of Jesus"? Mark 4:34 expounded only to his disciples. Why do you have to add?
There were only 12 apostles, but how many disciples were there ?
So, I wanted to emphasize that there were many more people who became disciples than were apostles.
Did you notice, for example, the number of followers as mentioned at Acts of the Apostles 2:41 ?
Only to those who really wanted to understand did Jesus explain - Mark 4:11-13; Matthew 13:13-15; Matthew 13:34-35; Luke 8:9-10