Yes, obviously the drug development process is very complex and a lot of thought goes into interactions at the N=1 level.
However, we are hardly at the point where drugs are developed for individuals, based on their genetic makeup. The best we can do (with exceptions) is design drugs for women/men, and this is a very recent development. In addition, per definition, a drug can only be effective/safe at the population level.
To make a very simple example, we think caffeine sensitivity has two distinct high/low genotypes. As a result, all recommendations of caffeine consumption will either be too high or too low.
I just go to about:profiles, and click on Launch profile in new browser.
I can use incognito mode, but this way I don't have to login, and keeps browsing history.