It's not only that. Players will always strive for "their best ship" no matter what, simply because this is a multiplayer team game.
If your group needs a healer, then why "I, the average player," should make the effort to grind for ages in order to be able to fulfil that role when anyone on the team may already have grinded for that.
With that logic, everyone will just go for their favourite ship and hope that they are put in a team where other people will have different stuff in order to make a somewhat balanced team.
"Why should I take the burden and the chore to grind and play with ships I don't like just to have a decent fleet, when everyone else will just grind for the only one or two ships they want to play?"
There's a reason why, in Overwatch, there's always that average Windowmaker in your Attack team that does absolutly not contribute to anything meaningful, but still keeps this character because that's the one this player wants to play.
The difference is that the rest of the team didn't had to grind anything to unlock the rest of the character's cast if they want to switch for a better team composition. And that difference is all it takes for people not to... basically grind their a*se off in order to be "credit to team" when the rest of the team didn't for very understandable reasons.
If the Dreadnought team really wanted to put the focus on your fleet and not only individual ships, they should've given the proper tools to do it, instead of doing the complete opposite.
People will never play this "fleet" thing if it's linked to the most unbearable thing in the game: grinding a tree of ships that you absolutly don't care about... multiple times.
That's probably the elephant in the room the devs completly missed. Somehow.
I agree with "everyone will just go for their favourite ship" sentence. Anyone who played WT/WoT know this feeling. In WT player has to have certain amount of on tier tanks(I played GF only, soo), so it forces players to research other things but game allows player to play one tank and research whatever player wants for small penalties/bonuses to exp. But ultimately, in WoT and WT most of people go for favorite tanks, or "best" ones. As you said, WoT-like grind-tier progression is totally against idea of having a fleet.
About WoT/WT like progression, as it was said many times before, historical tanks has to be separated by something so there was no choice. Progression like that in these games was implemented to solve that problem. There was no reason to implement progression like that in DN, it even created more problems. After reading your post I just realized that WoT or WT system allows for that grind-tier progression also because no one cares about team composition. In WoT people can't change tanks in battle so matchmaking tries to distribute tank types. In WT:GF it's just "use whatever you want". These games don't have most effective class compositions or anything like that because tank is a tank. In DN however we have classes that are very different and bad team composition often leads to defeat. As you said, if devs want players to have fleets, implementing 2.0 shipyard is completely opposite thing. Locking player to one ship like in WoT is against their "fleet" idea. Forcing people to unlock many ships of current tier before going to next like in WT:GF and forcing players to play ships they hate is equally bad idea. Even if people could research any position on manufacturer tree with one ship like in WT:GF, it also wouldn't fix everything because stock modules can be terrible and having bad module combination is just... bad. DN wasn't made for WoT grind-tier progression, devs will have to redesign entire game if they want to keep it and get rid of all problems 2.0 shipyard brought. Otherwise it will be a "meh" game for WoT or WT players. Devs want to change their target audience.