There is benefit in synergy.
Buying all within a brand does not necessarily guarantee synergy, so careful there. Some gear in some brand lines together might provide it, some not.
Don't forget also that whatever gear you buy has to synergize with the room and your listening position as well. That is equally important, perhaps even more so. You might also have to buy trusted consulting services to get that part right if not comfortable doing it yourself.
Buying all within a brand does not necessarily guarantee synergy, so careful there. Some gear in some brand lines together might provide it, some not.
Don't forget also that whatever gear you buy has to synergize with the room and your listening position as well. That is equally important, perhaps even more so. You might also have to buy trusted consulting services to get that part right if not comfortable doing it yourself.