I'm going to push back on this a bit. IMO, if a best strategy is not fun, then it is not the best strategy!
"Fun" is subjective though. There is a certain class of player who enjoys finding exploits and, well, exploiting them. Out of morbid curiosity, I've watched YouTube videos about the video game speed running community, and the way they "play" games is a combination of ridiculous skill and doing things that the game designers never intended.
TTRPG's differ, of course, because they are a collaborative group activity- just like you might be annoyed at a player in a battle royale deciding to exploit a rocket launcher to fly around the map at high speed, if the entire group isn't on board with an exploit, it's not going to, uh, fly.
It's one of the issues of the genre and why it's so hard to balance- different groups have different standards of "fun". There are groups out there who see no issue with the most broken and exploitative stuff in the game. There are also groups out there who absolutely despise characters who dare put their highest ability score in a prime attribute or selecting a species to play for any reason other than "they seem cool".
Threading the needle between two such extremes is never going to work right. You could make a game aimed in one direction or the other ("this is the game for hardcore simulationists. This other game is for casual gamists. This particular game is for deep customization options and embracing gonzo builds." and so on), but then you're devoted to having a niche product.
Games take time and money to develop. That makes it really hard to have a niche product, which is what D&D in particular struggles with. The people who want a game with an emphasis on class balance, tactical setpiece battles, and the ability to speed up out of combat play might not be the people who want to inch forward in a superdungeon with 11' poles and carefully tracking torches and rations. This leads to "cursed design" when a game is trying to present multiple methods of play within the same ruleset, unable to fully support one mode at the expense of another.
Control spells that lock down enemies are fun for their users, who like the tactical, almost Chess-like way of approaching combat, seeking the most optimal solutions. But they are typically less fun for everyone else.
For years, every time I would try to employ the Web spell, I'd watch as my own allies break out torches to try and get at stuck enemies. Why couldn't they just wait and kill them at their leisure? Because for them, that was boring! If your fun is wading into melee combat, slaughtering foes, it doesn't matter how cool a forcecage + sickening radiance combo is if it means you're not getting to perform your "cool thing".
In an AL game, we were attacked by Ogres. The Ogres wanted to get into melee and kill us. I used Sleet Storm to make this difficult, while the Druid used charges from his Staff of Swarming Insects to deal hefty damage to the Ogres. By the time an Ogre escaped, it was in a sorry state and easily dispatched. Nobody ended up needing any healing.
But who was having fun? Me and the Druid. The dual wielding Fighter was just sitting around waiting for an Ogre to escape. We had to yell at him multiple times "Do
not go in there or you'll die!". It wasn't fun for the Rogues, who couldn't effectively attack into a heavily obscured area. It certainly wasn't fun for the DM, who had to make checks and saves every round in the hopes of actually getting to attack the PC's with his monsters.
In my latest game, there was very little discussion among the players about their characters. I had a mini I'd been holding onto since before the pandemic- a centaur archer. I'd asked the other players if they wouldn't mind me not playing a spellcaster for once (I usually do, but I wanted a break from having to dither about each turn trying to select the perfect spell). "Oh, what class did you decide on?" "Fighter, I said."
When we all showed up at the table, and I had a bow using centaur with 12 Con and 50' speed who avoids melee combat like the plague, and the other players were a squishy Warlock, a Cleric who didn't even carry a weapon, intending on using Firebolt as their main attack, and a Barbarian, well, let's just say the Barbarian gets beat up a lot, because they're the easiest character for enemies to attack!
When not everyone at the table is built to have the same "fun", or worse, when one person's fun comes at the expense of others, that's a problem. But D&D isn't built with the idea that all the classes function equally or necessarily support each other like cogs in a machine. Quite often, everyone is doing their own thing at the same time.
You can attempt to mitigate this by having zero sessions and hoping your players get into "party optimization" instead of building their characters in secret without any collaboration- but this can backfire if you're not actually prepared to run the game for a group that has strong synergy!
The game could be built with characters having defined roles, and abilities that support each other as well, but as D&D found out, many players reject being forced into narrowly defined roles.
Player: "I want to play a Fighter with a big sword that mows down enemies!"
Designer: "Oh well, you see, the Fighter is actually a shield using bodyguard who deters enemies from attacking your allies."
Player: "That's lame!".
It also doesn't help that I want different things from a system as a player than I do as a GM. I love to play Pathfinder 1e and D&D 3.5 for example. I like having lots of options to help me build the character I want to play.
Being a GM for these systems is, however, a bookeeping nightmare, and I have to devote far too much time to prep for sessions, and it seems impossible to not have to stop the game frequently because nobody remembers a particular rule is!
I don't know what the solution is. I don't want to have to redesign a game to suit my needs. But unless I do, I'm never going to be fully happy with any system, because if someone is designing a game for me, it's likely going to be some small indie game nobody's ever heard of, that I'll never be able to convince anyone to run or play.
