One of my friends has a level 4 dragon yet his rank is lower than mine. When he attacks he always uses dragons.
As our rank goes up so does the toughness of enemies in war. So specialization seems to be advantageous.
The guy that only uses dragon is a lower rank than me and can attack weaker enemies. I have level 3 dragons and have to attack tougher enemies because my other troops (that I rarely used) are well leveled too.
Can anyone confirm?
Specializing occurs often in War Clans, especially clans of a specific TH level composed of small accounts of stronger players.
Specializing is good if you are going to stop at that TH level and only attack in wars. In other cases not upgrading all your troops will limit your experiences in this game.
Some people in these War Clans will even choose to not max their defenses to lower their "Strength" but have a army that they can 3 star with.
If you farm occasionally and don't rush your townhall, you will eventually have all of the upgrades anyways, so specialization shouldn't matter in the end.
However, along the way it is a great idea to max out each war troop before moving onto the next one, so specialization is a good thing while you journey to a maxed version of whatever TH you are at. For example, having lvl 3 drags is a lot more useful than lvl 2 drags and lvl 2 hogs to use in the same attack.
As mentioned in an above comment, offensive upgrades do not weigh much in war rankings so having all of the upgrades won't change your war weight, so don't worry about that when getting offensive upgrades!
