The creation of this tag seems like it would be very useful for linking so many similar questions together. However, whilst I support the creation of this tag, we need to nail down what the tag would cover.
We know that IRL food is off-topic, but, to play the devil’s advocate, would potions fall under the “drink” portion of the tag? What about the consumption of typically non-edible substances or materials? What about the consumption of living creatures? My answer to the question you linked would suggest d&d 5e does not consider creatures to be food as they are not objects. Do non-physical substances or energies which provide nutrition count as food?
As user V2Blast said in their answer, the tag will need a clearly defined description/wiki to explain it.
Also, we need to ensure we understand the scope of a potential re-tagging. As you rightly pointed out, there are currently 212 questions about food. However, there are also 195 questions about “drink”, excluding food (111 if we also exclude “potion”), 126 questions about “eat”, excluding food, drink and potion and 60 questions about “swallow”, excluding food, drink, eat and potion.
I’ve searched for other synonyms as well (again excluding the terms “food” and “drink” to avoid duplicates) such as sustenance, nutrients, nutrition, provisions and goodberry but all these produce single digit or low double-digit numbers, a negligible amount. Other terms such as consume or sustain are too broad to narrow down to only questions about food and drink.
This leaves us with a total of 593 questions which may need to be re-tagged, just under 280% of 212, the number of questions you estimated in your question.
I have not been around long enough to know if a re-tagging process would be so extensive. Indeed, 593 may be a trivial number compared to previous re-taggings, though I would not know as I have no frame of reference. My point though is that the number of questions which may need to be re-tagged is significantly higher than what you may have thought.
This also helps to demonstrate why such a tag is needed, there are around 600 different questions about food and drink but there is nothing to link them all together. There are probably more hidden behind overly obscure or overly broad synonyms, rendering them almost impossible to search for. A tag to collect them all in one place could help massively.