As they say no such thing as a free lunch.
Operating STOBAR comes at the cost of the payload of your fighter. Less weapons or fuel. The Jets also need to build up speed in their roll up to take off speed and the Ramp it’s self eats decks space so a lot of space is lost meaning a slower tempo of sorties.
All this and STOBAR still has equipment cost. The recovery wires, hydraulic Chock, Blast barriers, emergency nets are on the deck all need to be maintained and replaced regularly. You just don’t have the Steam cat or EMALS.
The Aircraft also have to be navalized anyway. The gear and tail hook beefed up due to the stresses of landing hard short on the deck as well as the throttle up to launch stressing the lead gear.
So really You have most of the Costs only a few of the benefits and more detrimental aspects. You get the larger recovery weight and that is it. If I haven’t made it clear I think STOBAR is stupid. It only really makes sense for small light aircraft like early carrier planes and some smaller drones.
So why go half arsed?
The Three STOBAR Navies all operate such because they got the design more or less second hand from the Soviets.
Russia only had one Carrier really, they didn’t have the Doctrine for a proper carrier. The Kuznetsov is more Guided missile Cruiser that moonlights in launching aircraft. They nearly lost it to Ukraine at the break up of the USSR. With the Russian crew basically stealing the ship. Its sister ship couldn’t move so she ended up in Ukraine until they sold it to China. The Successors couldn’t be built because Russia lacked the dry docks (Ukraine) and /or funding.
China operates STOBAR because they got the Second Kuznetsov class and Su33 from Ukraine and more or less reverse engineered the rest. They are now trying to transition to CATOBAR and more advanced fighters and their own Hawkeye knockoff.
India is STOBAR because the two carriers they have operate MiG 29K and one the INS Vikramaditya was a Russian VTOL Cruiser converted to a STOBAR. It even operated with the Russian Navy for a while. The Vikrant being built to use the same aircraft it made sense to be STOBAR. Yet the Indians too long planned to transition to CATOBAR with the long planed (and trapped in development hell Carrier intended to host Rafale.)