This has been disproven over and over again.
First an absolutely obvious reason that defys all further argumentation by itself: It already did work for a decade, when the System-Change did take 30-40 seconds due to the old system-change animation and slower internet-connections and machines. So, a delay of 30+ seconds from cyno-up to the reinforcements entering the field is exactly how the mechanic was designed when it was implemented.
Your biggest misconception is that you see Cynos as a “Tool to kill enemies!”. But that shouldn’t be the case. Cynos should be tools to reinforce an area, ensure dominance over a battlefield by bringing in huge support numbers and making the opponent break up their attack and flee - or escalate himself if he choses to. There is absolutely no need to be able to tackle, hold and then kill multiple ships of the opponent with the bridged/jumped in forces. The goal is to control the situation and thwart the enemy attempt to destroy your station, supercap, miningfleet or whatever is was doing there.
Second, you can open Cynos with HICs now, that can get beyond 200k eHP, which is more than a Battleship had in old times. I was able to create a Devoter fit with 250k eHP on Armor alone within 5 minutes of playing around in PyFa. This is way more than the usual Cyno-Domis or Armageddons had from 2003-2010 (hint: we didn’t have Navy 1600er plates or Reactive Hardeners back then nor would anyone afford T2 Trimark Rigs on a T1 battleship…).
Third, absolutely nobody forces you to open your Cyno within the optimal weapon range of the enemy fleet. You nullseccers have just totally forgotten how to fight. “Cyno Up, JumpJump, SpreadTackle!!!” is the only fighting style you know these days, because the game has pampered exactly this brainless blobbing for years.
Nobody forces you to jump in at 0m. Open the Cyno at 100km, bring in your fleet of properly fitted ships and MJD/MJFG on top of the hostiles. Bring enough RR or EWAR in the first wave, open another Cyno in the middle of the battle once you have disabled lots of the enemy firepower with EWAR or can place lots of RR on your second cynoship. Or keep using the first one for more reinforcements and ping via the next closes celestial or a mobile Interceptor warpin from the first wave.
Nobody even forces you to open your first Cyno even in Lockrange. Open it at 500km, bring in your fleet and warp down to the hostiles. This even opens up huge tactical gameplay options. The opponents can throw bubbles to delay you. You can throw defensive bubbles to protect your Cynoship. Your forces would have to make the right decisions which ping spots to use to arrive on the battlefield. You would be forced to use SmartbombCruisers to quickly remove Interdiction Probes or MJDs/MJFGs to move your ships out of delaying bubbles… and so on. FCs could really shine here. Personal skill would matter.
Nobody even forces you to open your first Cyno even on Grid. Bring in your fleet at the other end of the system, warp in from an angle they won’t expect.
Nobody even forces you to open your first Cyno even in the System itself. Open it next-system right on the gate, jump and warp to the battlefield.
All those tactics were viable and worked in the decades before hotdropping became a common curbstomping tool. It did work and it made it totally unviable to hotdrop roaming gangs to eradicate them on the fly, which was great, because small groups could actually go roaming in a bunch of cheap Cruisers, BCs and maybe a BS or two and just “brawl it out” when they found another gang that looked fightable. Without the threat of being hotdropped and totally obliterated without even having a chance to react.
So please Gerard, don’t argue with “that isn’t possible!” - It is. The only thing that needs to be done is to re-set the evolving of system-jump-speed that has naturally occured over the years due to better code, better connections and better machines. It wouldn’t even be a nerf, it would just be a reset to the intended mechanic like it was once implemented.