I would suggest a completely different format; this one is not suitable. Thank you all.
The current format should be primarily interesting to newcomers because, to win the tournament, the captain must be interested in improving their skills. I've been a captain twice and tried to give the players as much as I could, and it was very helpful for them. But if the captain is set on a "just play somehow" attitude, the team is unlikely to win. However, it should be noted that the captain's factor and the factor of team spirit are more valuable than having fewer participants in the team. In my opinion, 5 people in a team is too many.
The advantages of the "form your own team" format are that it's interesting for experienced players to compete against each other and for newcomers – the opportunity to play with experienced players. But there are also enough disadvantages with this system.