I believe the only way to prevent alt abuse in FA worlds is to restrict access to depths based on level size. for example an account with 2000 points reaches the next rank and may advance past the line of protection located at base levels 17-19 in most servers, at 12000 points they would gain access to the next tier of base levels assigned to that rank. In morale servers where depth is not an issue due to offence level constraints posed by malus, we still see the over use of alts to dig poi early on, however this solution of target availability based on account size or offence level would not work.
I also do not believe taking away players ability to use multi accounting to dig poi early is necessary. In most cases using multis does afford an advantage early on but mid level play mitigates those early advantages as we see the groups with the most players on side always win regardless of how good of a start any given team may have. I can provide many examples where this has been true and though i applaud the dedication of these types of players, far too many of them all play on the same teams which leaves us with this terrible imbalance we have been seeing server after server for the past few years.
To the common player things may seem not too broken and even to the staff that can see servers progressing far after the first few alliances have completed the fort, things may not appear too different than they have always been but i think since the topic of alts and the frustration at mega alliances dominating has gotten the attention of this games developers there must be something going on that is being noticed. I have witnessed the steady decline in participation of players not in medal contention in recent servers, especially from veteran players.
Placing blame isnt the answer and asking for something beyond the abilities of our current hosts is futile, so this discussion is worth it for me to participate in as i have a unique perspective on the past present and possibly the future of this game. My ten year anniversary is almost here and id love to be able to leave something behind for everyone that stays to play so my last suggestion here to you is this: please try to create a speed world that resets itself after the first fort completion and a short hiatus. Try to balance this server so that all participating teams can play with a chance to win for as long as possible because the winners of these most recent servers are being determined by week one and they are very disheartening to say the least.