That is not my experience at all. I fly non-stop between major US cities all the time. For smaller cities I may need to make a single connection.
I live on the east coast and within 45 minutes of 2 major airports. I just did some quick checking. Following are examples of the number of daily non-stops available from them:
San Francisco - 11
Las Angeles - 13
Dallas - 17
Seattle - 9
Portland - 4
Chicago - 33
St Louis - 9
Denver - 14
I fly to Little Rock, AR a couple of times a year. There are no non-stop flights but a quick search showed over 40 1-stop options from just the airport closest to me. Not all of those are going to be combinations most people want to do or are cost effective but if you throw away 1/2 if them that is still over 20 options. I also fly into Albuquerque, NM a couple of times a year. From my closest airport there are 58 1-stop options. If I drive 75 minutes to a further airport there are 4 non-stop flights to Albuquerque per week.
If you live in or near a smaller city served only by regional flights and are flying to another smaller city served only by regional flights than 2 stops will be necessary but 4 seems excessive.
Anecdotally, the reverse is not true. West to East non-stop flights have been scarce as of late to many major cities, even from a major hub, compared to a few years ago. Some flights in the same direction have sometimes been faster via Canada than staying the US.
Having had to do that quite frequently in the US, flights from West to East in my experience are much more likely to be non-stop hub to hub, or entirely unavailable.
The time difference and regional/hopper flights catering to "commuters" who need to fly early morning and late evening doesn't play well with the time zone changes, so you can either have a bunch of hopper flights with full day layovers at each airport, or you can catch an early morning long haul flight from a major hub airport to another major hub airport.
In fact I think I just saw an article (can't find the source) that talked about post pandemic the US domestic flights were much more focused on large volume hub-to-hub flights as a way of serving pre-pandemic customer levels despite understaffing.
An even quicker check showed 7 daily non-stop from San Francisco to my area and 4 non-stop from Portland. All of the Portland flights were red eye flights. I stopped counting but there were at least 30 1 stop flights from Portland with a layoff around an hour.
Well your experience contradicts both mine and my family's, the both of us living in two of the most major cities in the U.S. And there has absolutely been a dropoff of nonstop flights. Several used to exist and now literally none between areas I used to fly.
I live on the east coast and within 45 minutes of 2 major airports. I just did some quick checking. Following are examples of the number of daily non-stops available from them:
San Francisco - 11 Las Angeles - 13 Dallas - 17 Seattle - 9 Portland - 4 Chicago - 33 St Louis - 9 Denver - 14
I fly to Little Rock, AR a couple of times a year. There are no non-stop flights but a quick search showed over 40 1-stop options from just the airport closest to me. Not all of those are going to be combinations most people want to do or are cost effective but if you throw away 1/2 if them that is still over 20 options. I also fly into Albuquerque, NM a couple of times a year. From my closest airport there are 58 1-stop options. If I drive 75 minutes to a further airport there are 4 non-stop flights to Albuquerque per week.
If you live in or near a smaller city served only by regional flights and are flying to another smaller city served only by regional flights than 2 stops will be necessary but 4 seems excessive.