Lessee if we can keep this simple.
The difference between the Hydraulic lifter and a "Solid" lifter (or camshaft follower) is that the Hydraulic Lifter maintains it's own adjustment through rpm and usage wear. The Solid lifter tends to require maintenance and adjustment, often, frequently when used in racing applications . .
The advent of the Hydraulic Roller Lifter (or follower) was a normal but late progression of engine technology applied to the mass produced engines for greater efficiency and lower parasitic horsepower loss and, of course, less wear.
The problem that apparently kept the Roller lifters out of mass produced engines centered around getting the oil to the lifter because of the difference and location of the hydraulic component in the lifter body, along with the additional cost of more moving parts.
When the Engineers were given the newer casting and machining technologies that enabled them to overcome the oiling problems and the assembly problems that the new lifter created, "Voila!", Roller Cams for the grocery getter.
However . . Most of the Blown Nitro Engines and the GM Gen IV NASCAR engines all use Flat Tappet (Solid) lifters because of the less reciprocating weight in the valve train. The thought, at least in NASCAR, is to keep the valve train components as light as possible, the cam lobes as small as possible and to use the extended rocker arm ratios (1:8-1:9) to multiply the lift to compensate for the small size of the cam lobe . . Very low valve seat and opening pressures enable all of this . . It makes a large reduction in reciprocating mass, which we all know is one of the major "Engine Killers" . .
But this is predicated by use of the engine and types of induction. What works in one case, won't in another . .