You mean like the Park Street Under subway station in Boston? (There are two tracks and 3 platforms, the trains on both tracks are accessible from the center platform and the doors on both sides of every train open there.) With an added rule that the platform on the left (for example) or the odd-numbered platform is for boarding and the one on the right (or even numbered platform) is for exiting the train?
No one would ever be able to keep track of which is which for any given train, considering that some trains are moving East (towards Boston) and some are moving West (towards New Jersey) and sometimes an eastbound train has to use a track most commonly used by westbound trains and vice versa.
Of course this is just the minor problem. The huge problem is they would have to shut down and remove half of the tracks and install new platforms where those tracks are. They could get about a third of the lost capacity back by ripping out about half the remaining platforms and install new tracks where they are (reducing the total number of tracks by at least a third), or to keep the same number of tracks, widen the station and the tunnels under Manhattan by at least 50%. Greatly reducing capacity for decades during construction and hoping everything between 30th St and 34th St doesn't collapse into a giant pit while they're building it. They would have to move the pillars supporting millions of tons of skyscrapers that would block the new tracks. Got a couple of trillion bucks burning a hole in your pocket? It would be more useful to build a new 4-track tunnel under the Hudson and electrify every LD route in the country. Also buy enough equipment to run every LD train 3 times a day (every 8 hours), with hourly service on every corridor. Hey, we can all dream...