So RIOT what is your plan to stop the 3-5 man gank bot and get the tower + FTG at 6-7 minutes in?
Seriously, this is one of the more annoying additions to season 7. Bot tower is significantly weaker than the others, so poking down the tower before that large gank is easy and the damage done can be pretty significant too. So then the first team to gank and either cluster fuck the enemy bot lane or push them off of the tower will 100% always get that tower before anyone can even make it there to defend it.
This somewhat goes with one of the "weaknesses" in the ADC role too. Losing bot tower that early means that you cant really push out too far of your just a free kill from another gank. The ADC with the extra gold now has a large advantage over you, especially if they got FBG at the exact same time. Most ADCs cant even safely farm under tower with that kind of a gold difference pre 10 minutes (even pre level 6 sometimes). It is too great of a snowball catalyst for the bot lane who gets that FTG. And since there are very little alternative builds for ADCs, they can't just go more defensive to survive. They have to continue their expensive AF, high damage build or risk never being able to do anything in trades/group fights due to their lack of high damage items and/or core items.
I would suggest that FTG is not earned until 10 minutes in. If you have taken a tower prior to 10 minutes in, then no FTG is earned that game for either side.