So for me this was a very enlightening thread.
Soar/zgrssd, you are right, I think this is a balance issue. You start with the ability to get metal, food, water and if they aren't available you can trade for them. I didn't think of if that way before.
AKicebear, I had also not considered how tech discovery defeats the perfect build order chain, or certainly slows it down. In the last couple games I had put 40% into the Economic council 100% of which went into discovery (I like to play at the "slow" tech discovery rate). Unfortunately my Military council kept discovering things which in turn opened up more EC tech options. It seemed to put me into a power death spiral.
And zgrssd, I started my first "zgrssd start" at TL4. It's ok, but it just doesn't give the same "Road Warrior" vibe I get when I start at TL3, but I could learn to like it.
I don't see how this is possible, as discovering techs does NOT open up new tech groups - RESEARCHING them does !
While related, energy generation / antitank balance should probably be in different threads.
This discovery mechanic is actually a classic 4X trope : the first game to be given an XXXX rating (p92-93), Master of Orion 1 has this mechanic. Even worse, while some ("core") techs will always be available to research, half of the non-core techs will NOT ! At ALL ! (However the game does feature several ways to acquire the techs that you didn't roll from other empires.)
Then you have Sword of the Stars 1, which goes further, where (except for core techs) you roll links between techs rather than techs themselves, rolls which depend on your race. It did an IMHO admirable thing by not even allowing to get the techs themselves from other empires, but just their links : this does wonders for non-duel balance, where in other games it's generally very easy to run away with the game by becoming a tech broker. (Also, each tech might complete any time between 50% and 150%, and your chances grow the more time you take, which is another side to approach the efficiency issue compared to Shadow Empires BP inefficiencies per task and per empire.) You also don't see the full tech tree, only the techs for which you've rolled links.
SotS1 does see similar player complaints, the most common ones being not rolling (anti-missile) Point Defense (though experienced players know that many other alternatives to deal with missiles are possible) or Suspended Animation / Biomes (very important colonization techs, this is way worse, if you don't manage to beg for / salvage at least one of them fast enough, you're in deep trouble in non-duels), or your close opponent rolling light emitters (VERY good against masses of small ships, decent anti-missile, dedicated anti-emitter tech much more expensive and non-core either, though here too you have counters like snipers or just rushing a higher ship size).
Finally, there's the infamous SotS2 tech tree, where there's a "feasibility study" mechanic ON TOP of the tech links : you now see ALL of the potential tech links, but have no idea (for the non-core techs) whether you've rolled them or not : doing a feasibility study (~10% tech cost) will give you an idea about how likely that is in this specific game. Then you have to plow up to 150-200% in tech costs into that tech before you can know for sure - all those tech points might have been wasted ! (Oh, also, you can only research one tech at once, and accumulated techs points quickly disappear if you switch techs.)