This is probably going to be a bit of a ramble as I go into a full Monty Python " when I were a lad" post. Admittely this was decades ago but when I was in my teens I signed on S-forms for a provincial Scottish team ( aren't they all). We played continental teams frequently, and Italian teams were by far the worst for time wasting, flopping , faking injuries etc. We played Scadinavian teams, German, Austrian, French, Spanish etc. It wasn't even close. This was young kids playing friendlies mostly, it was like Italian kids were tought to do this, or it was in their DNA. We actually dreaded playing italian teams. We couldn't understand why kids who were for the most part, technically more gifted would resort to this type of cheating. Teams from Portugal and Spain tended to exaggerate injuries more than most but again, nothing compared to the Italians. It's kind of interesting looking back, Spanish players were the most prone to committing the " professional foul" , Italian players would put on a clinic in shirt pulling, and fouling while defending corners. There was the running joke that jerseys should be exchanged after the game not during, even though at that level jerseys were never exchanged. In general , there was certainly more emphasis on playing the "right" way, even players on your own team would ridicule you for play acting, diving, you got up and just got on with it.
I'm kind of spitballing here I'm not sure why it's become more of a blight on the game than in the 80's and 90's. Maybe it's because there's more money involved, there's more incentive to fake fouls, gain penalties, get the other players booked....sent off. One of the other general changes over the years has been players not playing to the whistle. If a player goes down, they immediately start complaining to the opposing team to knock the ball out. How many times do you see a situation where a player goes down, his team has the ball they continue their attack, lose posession, and immediately start shouting at the other team to kick the ball out.
As far as time wasting, one thing I would love to see change is the stadium clock showing the real time left. Meaning that during an injury, real or otherwise, the ref stops the clock. When players start going down like flies, the ref just points to his watch and stadium clock and says "fair enough, but you're not killing time off the clock". Not sure if that would make a difference.