You are very correct, online casinos are not really the best place to play card games for monetary profit, any one very talented on card games and want to play to make money, it is better to visit a physical casino where one can play one on one against a fellow gambler..
I think the only disadvantage of playing online poker is you can’t read your opponent mind and behaviour. Also online players often do risky bet such as all-in since they don't feel any pressure or fear behind the computer unlike actual which they can see their opponent. For a player like me that hates competition, I really like playing online because I can play against pro that can use mind games fair and square unlike physical competition which this pro is too intimidating.
Playing card games online should be majorly for fun, since you are only sure of the cards they system give to you, you never can know what is going on in the background with the cards owned by the system, winning online card games is always at the mercy of the system/algorithm.
This matter highly depends on the casino reputation that you are playing with. There is no benefit for the casino to rig the card system because they just subtract fee on the prize pot. The physical shuffle and algo shuffle is almost same in terms of shuffling the deck and card distribution.