Anecdote aside - unfair is not necessarily equivalent to undesirable. If you know the rules before you roll and agree to them, it's hard to call it unfair. (Unless it's one player - let's call them the DM - who insists on using certain rules that no one else at the table wants to use). But you can still call it undesirable. You can still say it's not as fun, even if it's fair according to the rules. Those collective groans suggest that it was suboptimal for no one to be able to play a paladin.
I don't think anyone is disagreeing that if the DM sets down table rules and you agree to them but they don't work out, the rule becomes unfair. The DM sets the rules, the players take it or leave it.
But a RAW system of character generation has been included in every edition of the game, and the nature of the RAW defines what the game assumes, even if the DM does change it for better or worse.
A good example is HP. Basic D&D assumed rolling for HP (1d4 mu and thief, d6 cleric, d8 fighter). HP is very low and 0 is dead. Basic assumed a lot of dead PCs. AD&D raised the hd size for all classes but magic users one step and included options for negative HP to raise PC survival, but rolled HP and 0 = death was still the default. 3e codified the common max HP at first level and negative HP as the RAW and not an option. 4e did away with rolling HP altogether and streamlined negative HP into death saves. 5e rolled it back with the OPTION to roll HP, with the assumption being fixed HP and 4e's death save. 5e also raised the HD for the lower HP classes like rogues and mages.
Now how you feel about that general trend towards increased sustainability of PCs depends on how fragile you liked your PCs. If you liked PCs who a kobold could sneeze and kill, this increased sustainability is bad. If you don't like going through a character a session and like to develop the one you have, extra survivability is a must to keep playing the character you like.
It reminds me of the combat as sport/combat as war analogy. People who want to play and explore a single character idea want a more sports-like combat, while those who favor more warlike combat don't mind death because soldiers die in wars all the time. The campaign is the focus, not the character.
That all being said, the game assumptions have very much shifted from campaign/war/randomness towards character/sport/survivability. That's been a trend for 30 years. Every edition has moved the game closer to that end because that's the end people have wanted. If lethality was a desirable goal, Max first level HP and negative HP rules wouldn't have gained traction to move from house rule to Core. If randomness was desirable, more class features like spells known would be randomized. If limitation as a method of world-building was desirable, we'd still have race/classed based minimums and maximums for ability scores and level limit and alignment restrictions on race and class.
But we don't. The market has spoken.