I would much prefer all of that over just giving them tons of economic bonuses I can never keep up with. (I'm currently playing Civ 6 on Immortal, where it's simply impossible to keep up at first, and I miss out on all of the wonders, but I still win in the end game simply because the AI is stupid.)
I remember Brad Wardell claiming Galactic Civilizations would have the best AI possible, and it was certainly decent, but players still identified plenty of situations where the AI was being stupid. Brad said he did that intentionally because doing otherwise would be too mean. Thing is, hardcore players did use all of those tricks. At the highest difficulty level, the AI should too.
Use the reasonable, nice, historical AI for the middle difficulty levels, but allow players to choose AI that is just desperate to win.
Since we're talking about freeciv, civ2 on deity is pretty easy if you know what you're doing. It's not even a forced way of playing, you can decide to win with just one city, or you can decide to spam cities with less than 3 population to avoid population penalties, and there's many other strategies.
If you don't know the game well enough to win at the highest difficulty, it is not degrading to play at lower difficulties to learn the ropes while still enjoying the game.
Watching a video of me playing Civ 6 would be incredibly boring. I take a long time, and most of the game I do nothing but desperately figure out how to keep up, and in the end I win with a boring Diplomatic Victory, unless someone else beats me to the Science Victory (other victories don't seem to be possible; except Domination, I suppose). They're not the most exciting games, but they're hard, mostly because it's impossible to keep up in science and wonders.
For my current game, I took a step back to Emperor level, though. I wanted to try an early game Domination Victory, chose Alexander the Great on Pangea and Epic speed, and it's just way too easy (except for holding on to conquered cities during a Dark Age).
I think I'm going to try the same thing on Immortal next. Maybe even slower speed so we spend more time in the lower tech levels where all Alexander's advantages are. And I need to start spying earlier; stealing tech boosts helps a lot in keeping up. I'm still not quite decided whether it's better to stick to a regular age all the time or flip between dark age and heroic age; Heroic Age is awesome, but hard to guarantee, and holding on to conquered cities is very hard during a dark age (I just learned that the Bread & Games project exists primarily for that situation; it helps a lot to have an entertainment district near your front lines).
I remember Brad Wardell claiming Galactic Civilizations would have the best AI possible, and it was certainly decent, but players still identified plenty of situations where the AI was being stupid. Brad said he did that intentionally because doing otherwise would be too mean. Thing is, hardcore players did use all of those tricks. At the highest difficulty level, the AI should too.
Use the reasonable, nice, historical AI for the middle difficulty levels, but allow players to choose AI that is just desperate to win.