YSK Squeezing a tea bag DOES make tea stronger, as well as healthier
It shouldn't really need to be said that if something is soaked and then squeezed, and the flavor of the output/product changes relative to simple soaking, that the resulting extract has become "stronger".
To give an example of a compound everyone is familiar with, in the case of tea, a typical 4 minute extraction leaves about 25% of the caffeine still trapped in the leaves. More important are the major antioxidants in green tea like EGCG, EGC, and EC. All of these have a bitter taste. They are all catechins (sometimes called tannins), and they all dramatically increase in concentration when a tea bag is squeezed. Catechins are flavonols/flavonoids, which are a type of polyphenol, and the ones found in green tea are often said to be some of the healthiest things a person can consume. Other teas like black and oolong have their own distinct polyphenols with their own, unique health benefits, but the concentration of all of them increases in your tea when the tea bag is squeezed. Almost all of these are bitter as well.
Why YSK: If you simply steep a tea bag for a few minutes and throw it away, you have discarded the bulk of the beneficial compounds that tea contains, and are most definitely drinking "weaker" tea.