#26, there are unlocks that allow for offensive situations but people aren't making enough use of them.
Soldier has the use of banners primarily the conch and battalions, there isn't situations where enough damage isn't done so buff banner isn't really necessary.
Sniper has jarate which doesn't take too much trouble to sync with a team. Throw it in a choke, hit one player then go for a fast uber exchange with the damage bonus or even send your roamer in after the jarate goes in.
Those above are the main ones for the current meta.
These below are ideas of what can be done or experimented with.
Demo has the quickie bomb which can destroy stickies for pushes, make space for bombs and just make pushes easier.
Pyro also has a scorch shot (I know this sounds dumb) however it destroys stickies as well and can help protect a team from bombs if the push is executed once the stickies are down. (I know this also needs a lot of experimentation as to who goes this class for this kind of scenario).
Medic has kritz which can always be a good go to option and vaccinator if the team is fast enough to work it with the bubbles.
This isn't really an unlock one but double spy is always a potential strat people can make use off.
All this brainstorming is good but making a 7cp map will just end in disaster. A major restriction on pushes right now is really closed chokes. Why would you want to push through a choke like gully to go for an uber exchange when you'll either die to spam or get forced really early into a horrible uber. Other chokes that suffer from this are reckoner, process, granary and snakewater sawmill.
Grass on snakewater allows the attackers to actually take ground and make plays so there's one advantage to that.
This is why the passive setup works so good cause the chokes are so hard to counter push that you can't make anything off just a roamer pick.
Badlands has good counterplays to this as the main choke is really open and also has an open valley which allows the attackers to make and take a lot of space.
I'm not saying all chokes need to be like this. However more maps need to offer the attackers some more room to breath when pushing from mid to second and vice versa when defenders can push mid with uber advantage.
Some solutions to these issues is to add in one more koth map which seems to be quite a popular opinion from what I read.
Personally, when Sideshow wanted gravelpit back for dreamhack, I liked it cause it will always mean teams have to push or just lose from the clock but I don't think that's a possibility. If it is, we would need 2/3 maps for a map cup to find any better contender than gravelpit.
The current maps just need to have some chokes reworked so teams can try pushing without having to worry about dying from spam instantly.
An example i'll give here is on badlands, a strat we use in Lego was to uber exchange from haunter, back out to choke, heal up six people on mid then go 6v4 on choke with both soldiers leading the charge focusing the demo so the demo cannot sticky off the choke while the team follows up. This strat only works here because off the openness of the choke. There isn't many, if any other map that allows this kind of play cause the spam you will receive will be too intense in a choke like granary choke.
TL:DR Summary.
There is enough unlocks to combat this no pushing style but teams need to actually try them and be creative with them.
The current maps are ok but the chokes can be reworked on a majority to allow for some offensive plays/strats/pushes.
An additional koth map could be good as a lot of people enjoy koth.
Teams actually need to sit down and create a few strats/ideas to play and improve. Only takes 15 minutes and can be very beneficial.