Except that in one case, RNG was intruding on gameplay and in all of the cases, the outcome of your laning phase depended with how lucky or unlucky you've gotten (dodge). Practically the same way crit Tryndamere still works, he can either crit you once or twice and you forfeit a kill. Then you start losing the lane from the get-go. Or he doesn't get lucky at all, he makes all the mistakes and starts losing from the get-go.
Where does RNG from the dragon buff cycler intrude on gameplay?
After you kill a dragon, you are immediately told which other buff is spawning in the next 6 minutes, so even if the buff is random, you have sufficient time to think of a strategy with your team and decide if the buff is worth contesting or not. The buffs are random because Riot didn't want people (especially pro teams) thinking of strategies that involve specific team comps that take off from specific preset buffs spawning and ignoring the unnecessary ones.
If Flame Dragon would spawn at specific times (let's say 1st spawn and 3rd), people would then always fight for those objectives, leading to predictable gameplay decisions and team comps evolving to be capable of fighting as early as level 4.
If Cloud Drake would spawn at specific times (let's say 4th and 6th), as the least valuable dragon buff, people wouldn't even go for it unless the it was free. it wouldn't be worth contesting or even trading for anything else so a team would clean it up only to make room for another dragon.
Honestly, fuck off with the complaints.
You're complaining for the sake of complaining. The PRNG Riot put into DBC and Plants isn't replacing skill for luck in your games as you have sufficient information before any of these things happen that let you know how the map will be evolving in the near future. This makes the gameplay portion of each SR game dynamic and unique. Because at any given time, your choices aren't exactly the same and the gameplay isn't something you need to practice enough times to be able to micromanage every decision.
On a macro level, everyone should know how the game works to know how and when to make proper decisions while on a micro level, player skill and finesse matters the most. This is what separates mediocre players from the great ones.