Actually, I find the suggestion wholly unreasonable. People don't buy first class tickets to need to BYO their tea any more than you buy a night in a 5* hotel to bring your own towels or go to a Michelin starred restaurant to bring your sugar for coffee.

I personally think of the trip as a trip and not as a hard core segmentation between various components which, quite frankly, have no reason to be segmented. I did not (and was not planning to) do it today, but I am no stranger to taking one herbal tea bag in the lounge to have onboard, and I similarly feel perfectly entitled to refill my bottle of sparkling water in the lounge. I also like reading foreign papers in a number of languages. They are not available onboard but are in some lounges and I have no issues picking a copy in the lounge to read onboard. If I do any of those things, it is always one (not 20) and always openly (I don't "hide").

Ultimately, it would be unpractical for any airline to cater to everyone's tastes and preferences. Say, there may be 100 ex-LHR BA premium pax a day who'll want to read a Spanish newspaper, 100 an Italian one, and 100 a French one, but it might be none or 1 or 2 on any given flight so it would make no sense to carry those at the gate. Similarly, I accept that some tea selections might only interest to few people to carry onboard, but if so, why not have more in the lounge and people can carry their own to the plane, why not. It seems to me that the premium lounges are a natural distribution point to cater to more tastes without over-constraining plane-loading. Many lounges worldwide carry paper coffee cups with tops and small bottles of water for that exact reason.