Whether or not a tripod can stably support a given camera plus lens depends on a lot of variables. By far my most wobbly and dangerously unstable tripod isn't really a tripod -- it's a monopod with three tiny spindly legs at the bottom. But in a museum or church with solid stable floors and no wind it will hold the longest heaviest lens I've got stable enough for very long pin sharp photographs provided I wait for around 20 seconds for the wobbling to stop after I last touched it. Then I fire it with a radio remote shutter trigger. Electronic first curtain shutter and no moving mirror means that it doesn't have to cope with mirror slap or shutter shock after the exposure is initiated. Boring and tedious, but good enough for pin sharp one minute exposures. As is leaning an ordinary monopod against a wall or bench etc..
I have a rather good ball head for my best tripods which isn't quite up to long heavy lenses. After I've composed the shot and tightened it up it droops down a bit. That's because the centre of gravity of the long lens and camera is well out in front of the ball head, exerting a strong twisting torque on the whole structure. Extremely annoying. So I bought a long quick release plate which let me place the ball head support right under the centre of gravity of the camera and lens. The result is a delightful absence of hands-off long lens droop.
I have no tripod which will keep a 500mm lens stable on a gusty hilltop. But even with my light travel tripod, if I pull down the centre column, fold in the last and flimsiest leg section, and hang my gear bag under the head (on the hook provided for that purpose), it becomes far more stable. That loses me a foot or so of height, but that never matters when I'm standing on top of a hill shooting something miles away. When I don't have a gear bag or I know the wind will be a real problem I'll sometimes carry a dog lead screw and a strong elastic luggage strap. That can exert a strong downwards pull on the stabilising hook, and has no tendency to swing in the wind.
The superiority of the most stable tripods only comes into play in certain conditions. If you rarely meet those conditions, and can stabilise your inferior tripod up to the required standard with a bit of problem solving, you can save a lot of money and a lot of weight.