Sincerely, you can do almost any exercise with a bar and bands. Watch an X-3 bar or competitor video. I own an x 3 and a competitor version. I have tested both extensively but I would rather not discuss the pros and cons here. I obviously own or have owned free weights, machines, dumbbells, kettlebells and almost every gadget that looked interesting. In my opinion it really comes down to what keeps you exercising. Is it the convenience of bands or the sound of clanking weights or the encouragement of a trainer or peers that motivates you? I think Dr Darden once wrote that the hardest thing about working out is to get to the gym. (Paraphrase.) The point is that the most important thing in working out is to actually work out.
With thick bands a bar needs to have revolving (swivel) ends. Curls and overhead presses are more difficult at the top. Bench press, tension increases as the bar moves away from the body but it seems to match the strength curve well. (Linear progression of resistance.) Squats with bands are typically limited to front squats on a platform. However, the reality is that doing a 30 second one rep with a band is “a lot of work.” You might have to start with a 15 second rep instead. Similarly, if an exercise is too easy, increasing the 10 reps to 15 reps or increasing the time under tension might help.
Bands are fast and convenient since you can do them as soon as you get out of bed. One possible use of dumbbells is a variation to get away from the bands for a change of pace to keep from getting bored.
Bands can also be attached to barbells, cable pull down and leg extensions to increase tension. I have tested leg extensions enhanced by bands and find that its possible to quickly increase explosiveness doing so.
I hope this helps.