Halyards are typically many times stronger than they need to be to get them large enough to be easy on the hands. Any loss in strength from a knot will have no effect on the functioning of the halyard. The benefits of being able to end for end and change wear points on the line is invaluable.

The reason you need eyesplices and shackles is to make work for riggers and jobs for shackle makers. Glad you've enjoyed adding to these people's livelihood that ultimately shortens the working life of your halyards.