I'm unconvinced that accepting large amounts of technical debt allows startups to react faster.
I've definitely seen startups that have almost found a good idea, but can't tweak it, scale it, or make it stable, because they're overwhelmed by technical debt and even simple changes have become engineering death marches.
Letting your back-end code turn into a complicated, disgusting mess means that adding critical features may become a multi-week nightmare. Which is then followed by a series of additional multi-week nightmares for each successive feature.
Now, this isn't to say that obsessive code-polishing is a good idea, either. But startups require rapid iteration, and you can't iterate especially rapidly when your code is complicated, badly organized, and poorly tested.
I've definitely seen startups that have almost found a good idea, but can't tweak it, scale it, or make it stable, because they're overwhelmed by technical debt and even simple changes have become engineering death marches.
Letting your back-end code turn into a complicated, disgusting mess means that adding critical features may become a multi-week nightmare. Which is then followed by a series of additional multi-week nightmares for each successive feature.
Now, this isn't to say that obsessive code-polishing is a good idea, either. But startups require rapid iteration, and you can't iterate especially rapidly when your code is complicated, badly organized, and poorly tested.