As AirportPlanner1 mentioned above, infrastructure is key. There just isn't the accommodation in most places to absorb any extra arrivals - my parents lived in Argyll during the late 80s, 90s, early 00s & had a second property on Tiree where they spent 4-5 months of the year (& lived full time for a couple) and planning trips on & off island was tricky even with accommodation. Travel/bed availability during some periods e.g. during the Wave Classic was challenging at best. Now that my folks have moved back to the Isle of Man things are no different - a limited peak season, limited accommodation (non existent availability during race weeks), weather dependent flights/ferries etc.. Any investment in tourism infrastructure would never be recouped during the limited season available. Maybe there is a chance, post pandemic, that a limited niche occasional charter/tour operator type operation could work, but even with a Loganair Saab/ATR42 operation 35-48 seats means a lot of beds to find.