Maybe for some... but the origins of it were there for generally good reason.
If everyone uses their cutlery the same way round when you have got three forks on one side, two spoons and a knife the other side, side plates, water glasses, wine glasses, dessert fork and spoon above... then thats tidy.
You avoid elbow clashing, people passing their knife/fork over their plate potentially clattering or dropping them, knocking their water or wine over the table.
Doesn't matter of course if you have one course or two courses and everyones got lots of room, but at a big table with everyone sat close and a huge place setting for each person, it does make a difference.
I don't understand why people pretend these dining and cutlery etiquette rules were invented for no reason or to upset others - they weren't at all.
It was about eating politely in a way that didn't infringe on others spaces, didn't ping food across the table, clatter cutlery or drop stuff or knock things over, or increase the risk of anyone dribbling soup down their fronts.
Some things were an effective code so that waiting staff could do their job without interrupting conversation - for example, indicating you've finished your course by putting your knife and fork on the plate, tines of the fork upwards, together, in the six oclock position, rather than putting them down apart, at an angle which indicates you are not yet finished with them.
Some were polite manners - salt on the side of the plate rather than sprinkled over, meaning you salted individually, and suggesting you had tasted it first rather than rudely assuming your meal to be under-seasoned by salting all of it.
Not scraping or mopping up the last scraps of food with a spoon or bit of bread - to do so risks you splatting it about, scraping noises that detract from conversation and suggests you are still ravenous and your host has underfed you (which would be VERY rude indeed).
Keeping elbows off the table/not leaning on the table - one I see commonly quoted as unnecessary and pointless.. again, at a tightly packed long table, someone doing this would be encroaching on the space of the persons either side of them, blocking their view of the table in general and likely meant they were attempting to converse with someone several seats down, which means talking across someone, which is very unpleasant for that person!
These things were also there so one could make a point if necessary! If you wanted to, you COULD indeed scrape at your plate or oversalt the whole dish, should you want to indicate to your host that they are undercatering and mean, or underseasoning and thus lacking taste and also, mean. To do these things didn't mean you were common... it might mean you're rude though (but being rude has never been a disqualifier for the upper classes has it!)
As far as I know from the time I have spent with the truly and genuinely posh upper class set.. it is the HEIGHT of poor taste and manners to remark upon (or giggle at, stare at or smirk at) someone elses lack of education in etiquette - such errors are down to lack of opportunity, and to remark on anothers poor fortune is a cheap shot indeed.