With a tensile strength of 6500 pounds you won't even come close, even from the reduced strength at the knot. The high strength of the line is associated with the low stretch characteristics, and a knot would be fine. The issue is a knot is less convenient (and less neat) since main halyards are often detached each time the boat is put to rest, and if that's the case the preferred knot type would be a bowline. Just make sure whoever does it knows how to make a proper knot without "pilot error".

Knots have worked for thousands of years.