However, the main darling of tagged templates, lit-html does exactly that: parsing, concatenating, then doing an element.innerHtml

So does HTM we discuss here.

I quickly googled. sql-tag and node-sql-template-strings do a lot of string concatenation (well, of course, they have to create a SQL statement out of values passed in). sql-template parses and concatenates.

Because it's really basically all you can do, be cause tag`string` is just a function call tag("string"). There's no magic.