In theory, the ball should leave the throwers hands and pass down the middle of both teams along the LoT. In the real world we normally allow some leeway - for example as long as it starts straight and stays at least between the teams. That leeway is dependent on the level of the teams - I’m giving 8 year old newbies way more than experienced adults.
If I insisted the ball stay exactly over the LoT for the full length of the lineout - well, with the teams I often see that would be a very tall order even on good days. I have to be practical in the application.
For me, the ball should enter the space between the first two players in the lineout on the LoT (or very close to it). Could be a couple of inches off the ground or 10ft at the 5m line, but must be over the LoT.
It should then at least stay between the players - if it started straight but by the last competing pair it’s still at least between them then I’ll play on to at least keep it flowing.
If it’s blowing down the pitch so hard that even a fast ball will drift wide before the end of the lineout, I expect the thrower to adjust and not throw as far, or the pack to catch near the front and understand that slow balls and longer throws are more impacted by wind than fast and short.
If this gives an advantage to one team, then it is usually only a slight advantage and it’s only on one side of the pitch. On the other line, sauce for the goose is also sauce for the gander. It will also be swapped in the next half.
We play an outdoor game, adjusting to the elements is part and parcel of that.