It may be noted that the Holy Roman Emperor more or less claimed to be the legal and rightful ruler of everywhere.
Some of the realms which claimed to be independent of the Holy Roman Empire in 1700 had been part of the Holy Roman Empire in earlier centuries, including Croatia, Hungary, Poland, Denmark, and possibly the Baltic states under the Teutonic Knights, and France.
The map in the original post is inaccurate about the borders of the Holy Roman Empire in the year 1700. During the War of the Spanish Succession the Austrian troops of Emperor Joseph I drove the French army out of northern Italy. Emperor Joseph collected millions of florins in Imperial War Tax from the states of northern Italy in 1708.
Several Italian territories including the Duchies of Mantua and Montferrat were confiscated from their rulers in 1708 for aiding the French. Possibly the Duke of Mantua and Montferrat was mislead into thinking northern Italy was not part of the Empire by looking at maps like that in the original post.
Furthermore, it is possible that some parts of south eastern France should be shown as within the borders of the Empire. At that time the King of France used a very simple title and didn't list all the many territories in France that he ruled.
From 1690, example:
Louis, par la grace de Dieu roy de France et de Navarre
"Louis, by the grace of God, King of France and of Navarre."
But in Provence and Forcalquier, parts of the Kingdom of Arles in the Holy Roman Empire, the King of France used the title of:
Louis, par la grace de Dieu, roy de France et de Navarre,
comte de Provence, Forcalquier et terres adjacentes
"Louis, by the grace of God, King of France and of Navarre, Count of Provence, Forcalquier and adjacent lands."
Thus acknowledging that Provence and Forcalquier were outside of the kingdom of France.
Starting in the Middle Ages for centuries a few rulers happened to inherit kingdoms, etc., outside the Holy Roman Empire and counties, duchies, etc. inside it.
Every single Catholic or Protestant Kingdom in early modern Europe sometimes had a monarch who also ruled states or fiefs within the Holy Roman Empire.
According to my answer here, for a few months in 1762 ten foreign rulers ruled fiefs in the Holy Roman Empire.
Which European nation had the most kings in the 18th century?1
Naturally it would have been good for the empire if an imperial nobleman who inherited a kingdom outside it decided to make it part of the Empire (despite possible strong opposition from his subjects) and pay tribute to the Emperor. The fact that was not done shows that imperial noblemen did not have a strong feeling of imperialism (i.e. loyalty to the Empire).