Oil is huge subject and never ending dispute.
From what I know it was not synthetic oils that cost engine troubles when they come on the market, but the dirt accumulated on engines that high-detergents in synthetics washed out. We had old Mercedes diesel, that closing on 300,000 miles was switch to synthetics.
Short time after the oil pump failed and the engine run for few minutes with no oil pressure at all. Would it be dino oil, the engine likely would be a junk. With synthetic it is still used in the family.
Using synthetic in my old boat might be not necessary, but I felt better not changing oil for 4 or 5 years. Boat run perfect and start each season without troubles.
YMMV