Your 'delay doesn't matter, the outcome will be the outcome' seems to forget some important aspects, IMO.
- Hospital capacity - If everyone gets exposure at once, ICUs overflow and mortality spikes for everyone needing care, not just covid. Delaying exposure litterally saved lives by flattening that peak. I really don't think this is an opinion.
- Treatment/vaccine timing - Someone infected in Jan 2020 had none of the treatments or vaccines available as opposed to someone infected in 2022. "when" you got exposed very much changed your odds of severity.
- Variant timing - You also seem to contradict yourself by saying the variant always mutates to being milder - which by that logic, delaying exposure means you might catch a less dangerous variant. That seems to be arguing both sides.
Your point about just 'isolate the elderly/immunocompromised...let everyone else go for herd immunity' starts to swerve into my area of expertise and I think it's flawed.
- It is practically impossible - As someone running a retirement community, I have staff that take care of residents, cook their meals, clean their apartments. Once those folks leave work, no matter how much we try to educated them on taking precautions, we have no control over what they do outside of work. They then come into our community and expose the residents to the outside world.
- Some of the worst when it came to compliance with our protocols were family. You would think, they would be the most sensitive to protecting their elderly family and other residents, but many were Not only non compliant or nonchalant, but some were outright combative.
Bottom line is that the 'you'll get it eventually' mentality as some sort of proof that timing and mitigation don't matter just completely ignores the fact that the avilability of treatment, vaccine and timing of the variants very much played a factor is how severely you got covid.