They can bring multiple dropships. I am not applying real-world limits, but many games limit you on tonnage, or have no limit (as far as I have played).
That is because they are nerds with no life. If they want to do that, they are playing fairly. Cause you had the option, and have the option. You denied that option. It's not like they limit certain players playing time, or who can pay for C-Bills.
I really can't express how wrong that is.
The bottom line is if they try to make metagame c-bill costs limit drops, the team with the most cash to burn would always have the massive advantage and that's a very bad idea. Now if they make the c-bill cost of 'mechs act as a BV style modifier (max c-bills per team) or otherwise balance it on similar factors, it'll hopefully mean far more even (and thus interesting) matches.
Notably this still leaves a reason to buy expensive 'mechs; if you want to take, say, 8 mediums 2 lights and 2 top-tier Assaults versus 6 mediums, 2 lights and 4 heavies balanced by a BV system with the Assaults costing the most to own/maintain, it'll still even out to be a fair fight team wise. I realize they plan to sell c-bills to upgrade 'mechs and that's fine as long as a team without it can match the overall capabilities.