Limiting new players to drop later doesn't teach them the FW=/=QP difference they might aim or have a better build but they still know nothing how to play FW properly. Unless sombody teach you the difference you will keep making the same mistake.
The
first few FW game i shot the gate not gen, i shot turret which where still closed, i shot the shell of the ogen or the gun of omega instead shooting the gens. Everybody
(tier 1-5) made that same mistake when they first played it until sombody showed/told you how to do it correctly. Those 300 quickplays din't magicly learned me how to shoot objectives or where to position in different maps.
I remeber when i first started the game i grinded myself 3 hunchies and 1 shadowhawk in quickplay because they where recomended for new players on forum.
However i did not know what FW was. Lucky i took kurita that had IS mech (since i din't know what clan or IS even mean that time) otherwise i had to use clan trials only. But i had to take trial heavy or assault to compensate the lack of tonnage i had with my mediums.
This is why i think
banning trial bad idea because most new players buying there first 4 mech are to try in QP they don't know FW IS/Clan restriction. If they bought 4 light or assualt or 4 not the same side they simply can't play FW not because they totaly newborns but simply
nobody teached them to plan for FW dropsdecks.
Restriction doesn't make new FW player better it only delays there question for *WTF AM I SUPPOSED TO DO!* You have to teach them either in-game, fighting with other people/units.
I am gratefull for my old unit CBR1 teaching me the basic FW when i was total greenhorn.
MS for letting me play in there group few times and showing difference with having a DC even though i was an outsider and the dropdeck suggestion since i couldn't plan my own drowndeck at that time.
EK open minded DC with some intresting tactics that i din't know you could pull off.
KCOM for letting me in there group when i showed in TS and they had spot open. They showed that playing aggresive works and that you had to play aggresive yourself if you wanna do some damage during the game

.
These are examples that helped me from a total newbie to an average skilled player but they all came from learning, teached and showed by veteran players how to do it.
Solo quickplay, my tier or my 3 hunchies and 1 shadowhawk did not teach how to be better FW newbie.