Restricting hand size to enforce Round 1 or concede right away is a silly and shocking (at least to me, given that I did not imagine they would consider something so ridiculous) solution to dry passing round 1, which only someone who has to go first would do, given that the disadvantage resulting from losing round 1 is at least better than getting outtempo'd round 1 and losing for certain.
The obvious solution would be to make it more desirable to ply round 1, whether you have to go first or not.
Swim's solution for that (a polished phantom point solution) would actually be an interesting way to deal with the issue (though a necessary change would be that one cannot pass after getting those points, given that the 3 turn limit would be inconsequential with that) and should in theory solve the issue, the point gain could also be a second stat on leaders to allow the idea to evolve with card changes and powercreep.
If there is a way to actually not be at the mercy of the player who goes second it does incentivice not losing round 1 and dry passing round 1 is always negative, given that you cannot dictate how long round 2 plays out and under normal circumstances lose "Last Say" during round 3.
Noone except a lunatic would willingly given up round 1, unless they have no other chance, which is why the hand limit "solution" only makes the issue worse and allows immediate reward (a.k.a. tempo / non-setup) decks to get a gamebreaking advantage.
If the coinflip issue gets fixed dry passing round 1 turns into a silly meme and passing round 2 is not getting addressed by this anways, if you play round 1 you would propably always get out 3+ cards and thus not care about that limit.
Beyond that the hand size limit breaks cards like avallach (at least in his current form), given that it allows players to immediately regain lost card advantage, paying for itself and being a silver spy on crack (if the opponent is at 9+ cards) as an opener or something like that.
Some may not like tempo being the main idea of getting card advantage, however having "uninteractive"/"unstoppable" means of getting it (a.k.a. silver spies) is an ever worse and less skillfull way to do that (which does not mean I disapprove of the existence of cards like the original ciri, which requires actual thought).