No. The principle behind RF is that in a large enough sample every player at the same position will see the same number of balls and the same types. Nubbers they have to charge, hard hit balls into the hole, deep IF pops, over time every SS sees the same number per inning in the field of these. It is not a perfect stat due to this assumption. In small samples, your idea of a variance of opportunity is true, but over careers it is a decent stat, moreso now than in the past due to the high amount of player turnover.
Loretta's 4.88 means nothing by itself. Actually, that is not true. It means he made 4.88 outs per 9 innings. But, without perspective that tells us nothing. The league average in the AL was 4.92, so he was slightly below average.
Now something else to consider, when trying to determine just the player's range, is F%. RF is dependent on how sure handed the player is. Loretta made very few errors, which is good, but in his RF that actually hides some of his range defficiency.
Saying Jeter doesn't perform well in fielding metrics due solely to less opportunities is a flat out fabrication. ZR, FRAA, F%, and UZR also all rate him below average for his career.