This does not mean that you should give up side control for the sole reason of submitting your opponent with a fly trap. If you are in a grappling match, giving up side control would cost you points or even being mounted and eventually getting submitted.
The consequences are even bigger if you give up side control in an MMA fight, you will be putting yourself in great danger of being attacked with ground and pound or getting mounted then attacked with punches and elbows and eventually falling into a submission.
The bottom line is, never give up side control, always stay in an advantageous position and don’t give anything up until you make sure that you will be able to counter.