First of all, if a member brings this art from a third party with some money and participates in this competition again, then why it will be accepted. If this is the rule then the admin you can get the design from all these sites fiver, upwork etc then this competition will not be needed.
I actually agree with your point but the fact that these people who are going to commissioned the artwork just for the sake of entering the competition will cost them a lot of money without the certainty of getting into top5. You are taking a lot of risk if you considered doing it.
Second from the previous contest i saw that many members used software to do this design but why would it be considered acceptable, Because drawing with your own hands and creating using software will be the same? Never same. If there use software for this competition then how can i do better than them with hand design?.
You can actually scale the quality of your artwork even if it is drawn using graphite/ charcoal medium if you can easily understand how tonal values works and how you can illustrate the mood of your concept.
The quality of the output actually depends on the level of your skills not on the medium you have used to create your entry.