Gain staging is something that causes a lot of people a lot more confusion than necessary. It doesn't matter at all if you're mixing in a modern DAW. Don't distort anything unless you want to. That's about it. A lot of the things we use in the box won't distort even if you want them to. In analog it's complicated a little by the noise floor, but honestly, the general rule is the same. Don't distort anything unless you want to. About everything in analog will distort at some point.
I feel like you might be leaving something on the table there. Not that you really always have to add a bunch of plugins on every bus, but there are some good things you can get out of your bus chain that can't get other ways very easily if at all. There may in fact be some things you're doing at a track level that could actually be better handled at the bus level. A lot of little things at various stages - track, group bus, master - can often be better than one big thing at just one stage.
In reverse order... It's not that I
don't use bus processing, and in situations where I'm looking at the bus as a single instrument - say, a bass guitar broken into low end and high end parts, or a bus combining two seperate mics on a stereo-mic'd guitar - then I absolutely treat the bus as if it was a single instrumental track and go to work on it as if it were. But, for example, if I'm bussing all the various parts of a drum kit into a single stereo drum submix, or if I'm taking a whole bunch of different (and not all doubling each other) rhythm guitar tracks into a single submix, then I'm way more likely to prcess at the track level than the bus level. Never say never, and I could see doing some light compression or maybe a mild EQ tweak at the bus level or something... But I feel like for the most part if I'm EQing rhythm guitars I'd rather go at it on the indivudual tracks.
Re: gain staging... Well... I suppose I could have said this more clearly, and to be fair I think it's probably initially more of a concern in tracking vs mixing (if I had a dime for every time I heard someone say you need to track as close to -0db as possible to "use up all the bits" but then have every track in the project turned down 6-12db...). But, when it comes to mixing, I think gain staging, or at least being AWARE of how the mix decisions you're making are impacting gain, definitely matters.
Like, if you're running a track through an EQ and boosting at 2.8khz by 3db... that's impacting track gain. Right off the bat when auditioning you're going to want to adjust output gain to try to balance the perceived volume so you're not preferring the EQ'd version just because it's louder, but far more importantly, that plugin is going to impact every single plugin downstream from it that has any sensitivity at all to gain. If that's it, then no harm no foul, the DAW won't internally clip so you're not really hurting anything... But, if you're running a track through an EQ and then into a compressor, then by selectively boosting a particular frequency band you're in turn changing the amplitude of the output signal, and making it look differently when it hits the front of the compressor... And, by clamping down on parts of the signal over a certain threshold, potentially changing how the EQ tweak is perceived as it passes through the
rest of your FX chain, etc.
With only one or two plugins you're probably not getting yourself into too much trouble, but if on your bass guitar you've got an EQ, a saturation plug, and two compressors, then unless you're really careful in setting up the gain staging and keep an eye on what exactly your FX settings are doing, then its possible to accidently start to overload the front of a compressor a lot harder than you meant to when, say, dialing in a little more saturation and some extra energy around 250hz. And, while at the end of the day it doesn't matter whats happening as long as it SOUNDS good, I'm kind of of the mindset that you want to make as much of this stuff as possible intentional choice and not happy accidents, and that unless you know for a fact hitting that first compressor harder because of the saturation and low end you added in is making the bass track gel a little more because you also went in and auditioned it with more "neutral" gain staging with the compressor hitting around the same way as it did before the new tweaks, then you're really rolling the dice.
Like, does that make sense? Gain within a DAW is totally clean even well over 0db internally... But plugins, especially ones trying to add some "analog" elements or that DO impact dynamics, absolutely need to be used with an eye on gain staging. At least, I think they do.