Short crankshafts are strong crankshafts. Engineering a crankshaft to withstand loads from 8 or 12 cylinders will be easier than designing one for 16 or 24 cylinders.
With a lot of cylinders in quest for great power, it might be prudent to 'split' the load. A 16 or 24 cylinder liquid-cooled engine might have it far easier if it has two crankshafts (Sabre, Fairey 16 and 24 cyl types, V-3420, DB 606/610) than with just one (RR Vulture, Jumo 222).