It is not just about winter pressures easing and summer being the best time to deal with it, and herd immunity........don’t go there on that one.
By elongating the phase of people getting it it flattens the peak. Essentially imagine a situation where you had 30 beds available. A massive spike, they are all filled day 1. These people need intensive nursing care for 2-3 weeks at a time. The following day another 30 will need beds - no where to put them, staff at risk etc. And so forth
If you can get them in in 2’s and 3’s and by the time the first ones are better, their beds are available then they can go into that.
Think a babbling brook as opposed to a waterfall.
Its why social distancing and appropriate isolation is important