I suspect (but not 100% sure) if it's 2000 lms output over a small projector area (xenon type) output, washers are required. However in Seat LEDs, they are over mutiple LED units, each individual light source lights up less than 2000lm each, but perhaps over the 5-6 separate LEDs it may give a total of 2000+ Lumens. Also I did notice the Mercs and BMWs also do not have these washers, but they tend to have 2x LED units per headlight unit or 4 in total. Perhaps 1500lms per LED unit, total more than 2000. However if you notice the current Audi A3 where it's 1 LED light source per headlamp, there are the washers as standard. Washers tend to drain the washing tank VERY quickly.
I guess Leds don't cause as much glare as their xenon counterparts, when the headlamps are dirty, but from experience, when it's dirty, the light output can drop noticeably on Leon LEDs, but on xenon (on
Ibiza) they are still pretty bright.
My 2013 Leon 'first car in segment to offer full LED headlights' had headlight washers as standard, without winter pack. Perhaps at the time, included them to play it safe. 2014 models onwards only with winter pack.
I mean if you give your headlights a good wipe with a wet sponge and then a microfibre cloth to dry it off, every once in a while it should be fine.