Citation needed.

As far as my personal observations go, Google is NOT optimized for long tail at all. It is always trying to return most popular results from cache of most popular results. Once the cache is exhausted, Google starts to return completely irrelevant trash (anything after first two pages of search is pure spam and meaningless keyword soup).

If you try to look up some obscure keyword and find nothing, try again after couple of months. There is a very high likehood, that you will see dozens of "new" results — most of them being from several years old pages. Perhaps, the actual long-tail searches still happen somewhere in background, but you are not going to see their output right away — instead you need to wait until they get committed to the nearby cache.

Another alarming change, that happened relatively recently (4-5 years ago), is tendency to increase number of results at expense of match precision. A long time ago Google actually returned exact results when you quoted search phrase. Then they started to ignore quotes. Then they started to ignore some of search terms, if doing so results in greater number of results. Finally, Google gained horrifying ability to ignore MOST of search terms. OP's example probably has the same cause — Google's NLP knows the meaning of word "without". But Alphabet Inc. can't afford to hose all those websites, that use AdWords to sell you STRIPED SHIRTS. This would mean a loss of money! THE LOSS OF MONEY!!!