That would be true if you were exporting all the time.
But most exports tend to happen around peak times, as that is when you will have filled the battery up, and the times of year when it is not still light then you won't be exporting much anyhow.
This month, my export has averaged 12.3p per kWh. But I'm not exporting anything at the peak rates.
There are pluses and minuses to both ways of doing (or their third way - Flux).
I've just had solar installed and they recommended Flux. For some reason it'll take them a couple of weeks to get export allowed, so it's battery and import only for now.
Rates are
I think the way to best manage this is:
Winter: charge up the battery fully at cheap import overnight. Recharge a little bit if needed just before the peak rate kicks in
Summer: discharge the battery to maybe 25% during peak rate. Charge up to maybe 20% overnight to get you to when solar kicks in.
No idea if this is really the best octopus tariff for us, or if others are better. So many options, I'll go with this recommendation for now.