As someone who's been both at top startups as well as boring tech companies, my experience suggests that it's not as much a difference of tech stacks or skills

As someone who's been both at top startups as well as boring tech companies, my experience suggests that it's not as much a difference of tech stacks or skills as opposed to priorities. For better or worse, in a lot of tech companies, tech wins hands-down. It has to be the "right" kind of tech (suggesting pragmatic but old-school solutions not fitting the current groupthink might not pan out), but generally, tech nevertheless works (maybe because there are enough resume-driven-developers that regardless of management/politics concerns, pushing for the right tech will always get enough people on your side to win). In legacy companies, tech alone won't get you very far regardless of its merits - if anything it's the opposite. "Too much" tech will actually be seen as a threat and you may encounter roadblocks, because the tech you're proposing is too good and will threaten some entrenched positions or entire departments within the company. If you want to succeed as a tech guy in a big legacy company as an employee, you need to stay within your lane and not push the boundaries - the boundaries you are being given (explicitly - or implicitly as in "why hasn't this been done before? this seems so easy") are there for a reason and are there to protect some position(s), and unless you have a direct relationship with the CEO and/or investors, you are unlikely to win this battle (it took me a firing to actually understand that). Remember that you may be hired to provide business value as much as you could be hired to be a number on some manager's direct report's list where your only true job is to pad that list and otherwise not rock the boat too much. On the other hand if you determine the limits and manage to automate day-to-day tasks well or at the very least automate the BS and make your workday enjoyable, it can be a nice cushy job that only require a couple hours a day - not to mention that doing the right favours to the right people will give you good career progression (if the company itself appears to be on solid foundations). Of course, please do any of the juniors a favour and try to explain them these dynamics in private, so they don't shoot themselves in the foot early and get fired by threatening some high-up position/department. TLDR: don't join a legacy company because of passion, but join it if you're ready to put morals/perfectionism aside and make a decent bit of dough. The reason their tech is so shit is not because of lack of skills or money but because a lot of existing money depends on nobody having those skills. If you can operate within that environment you will have a good time.