A starship can:
Orbit and study an entire planet in hours.
Approach and study an anomaly in space.
Carry hundreds of people at once (engineers, specialists).
Carry dozens of well equipped laboratories.
Launch several support craft to different locations.
Wage war with powerful weapons in space and orbit.
Carry cargo in emense quantities quickly.
Carry equipment and supplies that are too unstable to be beamed at all.
Mine materials from celestial masses or nebulae.
Take a fully assembled machine to a specific location.
Deploy objects into space or orbit of a planet (comms/satellites).
Retrieve objects adrift.
Aid evacuation en masse.
Etc, lets see transwarp beaming replace all of that overnight, then I'll believe it makes an organised Starfleet redundant.
Even better, thank you! You've thought this through even more than I have. I'm saving all this for the next time I see the "they don't need starships" snipe show up in a thread.