Sure. I'd not be able to actually do anything useful with a gigabyte single-line file so what I'd want my editor to do is say "Longest line is over 100k characters, truncating display to the first 100k".
issue is that the editor can't tell if it's a multiline file with a first big line or an editor with one big line if it's cut at the first line. But I'd rather have the editor bail at the first 100k line than not opening it.
If it's over 1 GB and single line you're almost always going to exit the editor, run some scripts on it, and open it again when it's correctly formatted.
Most of the time I only realize that everything is on a single line after opening the file.
A good editor doesn't require me to think about these things.