The high tech factions yes. They tend to have the strongest mixed fleets. But not the high tech ships. Its the fact that low tech factions field the *** low tech ships rather than having a strong fleet doctrine that really saves the high tech fleets. That and the fact that they tend to just be bigger in terms of total RC. And you are not limited to fielding (D) Combat Freighters and Shuttles
And in a 1v1, yea, sure, the high tech ship may win. But the game isn't a series of 10 1v1's right after each other where you slam 20 RC ships into 30RC ships until the victor is decided. Its a fleet combat game and you start with at least two combat capable ships right from the get go.
The strongest high tech ship is the Astral, and its not really a "high tech ship" its a carrier. The next strongest carrier is the Heron, not a high tech ship. The next strongest carrier is the Drover. Again not high tech. The Astral is only good in a strike role, because the other carriers bring more ordinance per RC and the Astral cannot utilize recall effectively on interceptors.
The strongest warship is the Onslaught(not high tech), followed by the Odyssey or Paragon(depending on skills), followed by the conquest(not high tech), and then the Eagle and Falcon(not high tech), or maybe the Dominator (not high tech), then either the Gryphon or the Sunder, then the Hammerhead then Enforcer(of which only one is high tech and the Sunder requires both ITU and Advanced Optics AND access to tachyon beams or High Intensity Lasers to be particularly effective). This list might change depending on how you value your RC, but its not going to put weaker and more expensive ships like the Paragon on top.
The best frigate is the Monitor(not high tech) and then the Omen, then the Brawler(the regular Brawler not the TT version) and then probably the Kite(a). And the Brawler might be better than the Omen.
A few of the phase ships are particularly effective in the hands of a player, but not so much so in the hands of AI against a properly partitioned fleet. They're too expensive and they run out of CR too fast. For every Shade you bring you could have brought a Hammerhead. For 5 more supply of a Doom you could bring an Onslaught. For every Harbinger phase destroyer you could bring a Heron.
Tell me, would you rather have a fleet of 4 Paragons or 5 Onslaughts? The paragons wouldn't even have time to raise their shields before they would be flux locked and dead. Would you rather have 4 Medusa's or 6 Hammerheads? The Hammerheads would fill the air with so much lead the Medusas would only be able to phase skip into more lead.
"High tech" weapons are generally weaker than low tech weapons all things equal. They're better in specific circumstances but you have to have a very distinct purpose to everything. The only 1000 range energy weapons are beams and beams cannot generate hard flux. The next longest range is 700 which only come in a large size*... they're 200 range below the Large Kinetic Ballistics, 300 below the Medium Kinetic Ballistics, and 100 below to even with the Small Kinetic Ballistics. Flack Cannons do not have an equivalent high tech weapon and flack cannons are civilization. Energy weapon has only one HE option.In the long range high tech weapon category until you get to large size you've got Graviton Beams, Tactical Lasers, and Ion Beams. Graviton beams are great, especially if you have a lot of them... for killing shields. Tactical lasers are ***. And Ion Beams are great, if expensive, if you can EMP lock something and if you can generate the hard flux needed to arc through the shields in the first place, otherwise you're just paying 150 flux per second to the enemy. The only really particularly good long range energy weapons are the HIL and the Tachyon lance... which require large fittings... which require a Sunder, Odyssey, Paragon, or Apogee.
*The exception being the Thermal Pulse Cannon but well, that only comes on the Onslaught