If it grows at O(n) it is not a startup in the way "startup" is used in Silicon Valley. It is just an ordinary new business.
It's worth noting that starting an ordinary new business is hard. Probably as hard as starting a startup for anyone who has not started a new business a few times before. And maybe harder because most new businesses are undercapitalized and therefore likely to suck up personal capital while startups get to use other people's money.
Perhaps they are harder to start, but they are also vastly more likely to succeed to their O(n^2), and this is not only due to the increased barrier to entry.
That's what I mean when I say, founders are more likely to succeed at O(n) companies.
Very few have successful exits where the owner walks away with life changing money and no obligation.
(For example, you get successful enough that you need a bit of office space. Well, your little business is not going to persuade anyone with nice office space to lease to it alone... Landlords will instead demand the owners personally guarantee the lease, i.e. commit to paying it or go bankrupt trying, even if the business shrinks and no longer needs or can afford the space. So you thought, great, we had a couple years of strong growth. Now you get to commit personally to five years of a huge expense. Congratulations.)
Typically, new businesses don’t get very much credit on favorable terms without established commercial relationships.
Dealing with failing or failed businesses is just not worth the hassle for most established businesses working in the established business market segment.
Silicon Valley is probably different because the business relationships are different. And of course month to month and short lease real estate are an entirely different market segment than triple-net.
A hungry landlord is a landlord who is in dire financial straights.
Good landlords can afford to wait because they are using real-estate to park wealth, not as a means of putting food on the table. Think insurance company reserves and House of Windsor. It is a long play.