Starfleet is Age of Sail. It comes close to US Navy when it was created, not today's US Navy.
Original US Navy was an extension of politics where they didn't interfere in other affairs, it was there to protect US territory and shipping.
Six heavy frigates (heavy cruisers in ST universe) were built to help accomplish this goal, US had no Ships of the Line (Battleships) like British Empire.
Very similar philosophies between early US and Federation.