I don't know how old you are, but I'm 58 and that is the viewpoint I'm coming from.
Physically taxing is a given. The court gets relatively larger every year as we get older. Shots that we could have easily reached now require a serious, concerted, and high effort movement to reach and execute a stroke. As much as I have tried to maintain my stride length, I need one extra step now to get from the center hash to the sidelines than I needed ten years ago. Good drop shots are an all out sprint. And this is despite working out, a lot. I spend at least ten hours a week in the gym, and I bet I am stronger than 95% of tennis players of any age. I can squat 350 pounds and bench press 225 pounds easily. During the summer, I do run sprint training and participate in day-long endurance events. Strength is not an issue, but elasticity and speed of contraction of muscles is, and that affects speed of movement.
Modern strokes require a lot of rapid and coordinated muscular contractions and interactions. This also gets more difficult as we get older. We may still be able to use the technique, but racquet head speed slows down, and the ability to repeatedly generate the same stroke with correct timing while hitting the ball on the sweetspot, diminishes. Eyesight gets worse. We can't change our focus on the ball from the opponent's baseline to near the hitting zone as quickly. The ability of the eyes to track a moving object, called a saccade, diminishes. These eye movements become less accurate and combined with the slower focus once our eyes become stationary, leads to more mis-hits and worse timing. Reaction time diminishes. Fine balance diminishes. Never more noticeable than descending a curvy road fast on a bicycle, or even driving in a high performance event on a track. It takes longer and bigger inputs before I notice things, and in tennis that means that my balance isn't as good when I get twisted around or are scrambling to recover to the middle of the court.
So at some point, there are diminishing returns. The modern technique may be there, but with decreasing physical ability the effort to generate it may result in a ball that an opponent with a large headed racquet can easily neutralize. The risk/reward isn't worth it, and it's better to use a less complicated stroke and use ball directionality versus spin or ball speed. A less complicated stroke can also be executed better with a more forgiving racquet, which is why in one semifinal at last year's gold ball indoor 60's tournament, three of the four players were using extreme OS racquets.
This is no different than in any other sport. If Nolan Ryan were to play age competitive baseball at age 60, there's no way he can throw 100 MPH any more. He's probably lucky to get it up to 70 MPH at age 60, and so he can't just throw it past people any more. He's got to move the ball around the corners of the plate, throw in change ups, and not just fire it down the middle of the plate.
I take it that by asking your question, you're not as old as I am. Enjoy the physicality you now have, and really, really relish what you can do on a court because at some point, those things will only be a memory. I wish I had the foresight to enjoy what I could do back in my 30's and 40's.