The way I see it - and I have one child who spells the 'outlying' words in a very wide vocabulary phonetically and one who spells absolutely correctly but thereby chooses to restrict their vocabulary slightly when writing - is that children as they learn to write have to master and deploy a wide range of skills, e.g. physical handwriting, spelling, word choice, sentence construction, grammar, paragraphing, composition of an entire piece of writing in terms of plot / organisation, knowledge of genre.
It seems to me that it is appropriate to, in the early stages of writing, focus on these fairly individually, and then require children to orchestrate more and more of them at the same time as they become more skilled.
So, for example, in a lesson focusing on writing an exciting story, using ambitious vocabulary and choosing punctuation for effect, I would not necessarily pick up on every spelling mistake, unless it was in 'core' words that I would expect a child at that age or stage to spell. So I would nitpick on the spelling of 'your', but not if a child wrote 'sintillating' as a real stretch to their vocabulary.
On the other hand, in an exercise focusing on spelling, every spelling would be checked.
Once an older child - middle to later primary - has reached the stage of reasonable mastery of the whole range of writing skills, then I would expect more of them to be routinely correct.
It's not a case of 'learning it wrong then having to re-learn it' - it's a metter of focusing on one or a few skills at a time to explicitly teach them to a high standard before then teaching the skills of synthesis which bring all those acquired skills together.
If I learn a new skill - let us say table tennis - at the early stages, and today's new element of the game is imparting backspin. I will progress much better if, just today, I am allowed to focus on backspin, which may mean that e.g. my ball placement or my serve may be less effective than it was in a previous lesson on that aspect of the game. By working solely on my backspin today, I actually hasten the day when I can bring all the skills together at a high level in the game. If today you not only make me do backspin but ALSO pick me up every time my ball placement isn't perfect, I will in fact progress uch less fast, not only on my backspin but also on the rest of my game. I believe that the same principle applies to writing - that explicit focus on one or a few skills, while temporarily, for that lesson, allowing reduced focus on the others, will hasten progress more than requiring all skills to be perfect all of the time.
That is NOT to say that I do not expect words in a child's core spelling vocabulary to be spelt correctly all of the time. But I would not expect words in their 'outlying' vocabulary to be so spelt IF the focus were to be esewhere today.