As I said before, I´ve never said that the classes are less unique, I said that a class could fulfill a lot of roles, so it doesn´t matter if you do not have a cleric, a warrior of a rogue in the party, for example, because there are many other classes that could do their job, even more than in previous editions. Also never said I liked it that way, I was exposing bare facts.

You do not seem to understand that the skills, saves and attack rolls in 5e are calculated by 2 things: Proficiency and stat. And ANY CHARACTER has the SAME proficiency number at the same level with their trained skills. And the background, some subclasses and feats allow you to train in skills outside your class.

A wizard or cleric trained in survival or animal handling(ie. outlander or folk hero background) with wisdom enough would be as skilled as a ranger living in the wild. They will have EXACTLY the same skill number: With 14 wis your wizard or cleric will have +4 at level 1 +5 at level 5 +6 at level 9 . etc Same as your Ranger. Possibly even better than your ranger in the long run because clerics usually have more wisdom.

That means that a fighter or a rogue trained in medicine with the same wisdom stat would treat wounds, stabilize your fallen party member and identify diseases as well as your cleric or your druid.

A wizard with high investigation could be better than some rogues at detecting traps because they possibly have higher int and could be trained in thieve´s tools as any other character with the criminal background, for example.

Any wizard or artificer are potentially better than any cleric or druid at knowledge nature and religion because the main stat is INT, not WIS (and those classes usually have much more) so they could take care of the tasks that require it without a divine spellcaster.

A barbarian trained in arcana (just pick the sage background) with 14 int would have the same number in arcana as a sorcerer with the same int of the same level.

Your sorcerer, warlock or paladin could be much more intimidating or charming than your fighter or your barbarian or rogue because those classes usually do not need CHA.
Your barbarian, wizard or rogue could be as skilled as your bard at performing because there are several backgrounds and feats that allow you to be trained in performance or a particular instrument of your choice.

The only difference could be rogues and bards that could get specialization in some skills so they could be better than average at several skills.

Anyone could take a look at how character creation and classes/subclasses work at 5e and take a look for himself. That´s the jam now in 5e.
Heck, even now with the Tasha´s new book you´re not even restrained by the races` and you could pick your own: ¿You want a half-orc with +2 dex and the stealthy feature? you can.

That also means that a sorcerer has the same hit% that a Barbarian or a fighter if they have the same weapon and the same Dex/STR. There are even lots of subclasses that allows bards, warlocks or clerics to have armor proficiences and the same attacks/turn as a barbarian, paladin or a ranger, so you may forfeit your frontine warrior and use one bard, warlock or cleric build instead without even multiclassing.

If you do not have a rogue or a ranger, your druid or your wizard could be your scout and use the thieve´s tools. If you do not have a cleric or a druid your ranger or your celestial warlock or sorcerer could do the healing, your rogue or barbarian could be your diplomat, your bard your melee fighter, your cleric could be as good at tame animals, using survival skills and spot creatures(still retaining their healer role), etc etc.
You may tell me that a warrior would do warrior stuff, a healer would heal or a rogue would do trickery stuff at 100% efficiency, but there are many other classes that could do that at a 90% efficiency. So yeah, you win, there´s a difference, there are classes better suited for a particular role, but that does not mean that plenty other builds that could cover for it if you do not have/want that class in your party in 5e.

Played lots of games without a cleric, a rogue or a warrior and find that the party could do fine without them because other classes could cover it without much of a fuss.When you are playing you do not notice the difference that much, unless for very situational roles ( i.e. A cleric in a tomb full of undead would be useful to turn them, a bard, ranger, druid or a Firbolg if you want to talk with some plants or forest inhabitants, etc)