Single-Camera and Mockumentary
Comedy without laughter was long held to be difficult: viewers would not know where to laugh. This section is where that assumption loosened.
Seinfeld is often said to have used no laugh track. That seems to be slightly off. By the testimony of one of its directors, laughter was not added or boosted in the edit or the final mix; more often, laughter that covered a line was cut. It is also reported that a little was added, sparingly, to location scenes with no audience, so that they would not feel out of step. Closer to the truth than "did not use it" is "live laughter as a rule, and more cut than added."
The Office (US), from 2005, carried over the British version's documentary form and its no-laughter policy as they were. A character turns their eyes to the camera — and that look, in place of laughter, carries the sense that someone is watching. It ran for nine seasons and 201 episodes.
Declaring that this changed the standard for sitcoms may be a little early, though. In 2011, when Modern Family was sweeping the awards, the top ten in the ratings was reported to be held instead by shows with audiences. What changed was the standard in awards and criticism, and how much easier it became to get the next project made. Television's standard can move separately in awards and in numbers.