The other major issue with convertible notes are that entrepreneurs can end up giving away a lot more of the company than they realize. For example, if the company does a priced round with a pre-money valuation less than the cap (or with uncapped notes, less than expected.)
The median pre-money Series A valuation for all WSGR startups is ~$8.0m [1], which is likely on the higher end.
Also, uncapped notes do not get diluted when raising your Series A, which is additional dilution for the entrepreneur.
For example, let's say you raise $5m uncapped notes with no discount. If you then raise a $3m Series A at a $8m pre-money valuation, you'll end up giving away more than 50% of your company, not counting interest or option pool. At a $15m pre-money valuation, you'll be giving away over 40% of your company.
Entrepreneurs should be equally careful with SAFEs.
If you raise $8M in funding and your company is only valued at $11M, then you deserve to own less than 50% of your company since investors could have done almost as well sticking their money into a bank account.
I don't think the numbers given in your example are particularly realistic. Series A rounds are almost never smaller than seed rounds and are usually at least 3x - 10x.
My point is that entrepreneurs can get into jams inadvertently.
If you raise $2m or $3m on uncapped, no-discount notes, you basically need to turn that into a $10m+ pre-money company upon raising your Series A. If you raise $4m or 5m+ seed, it gets even harder. And this is assuming no cap or discount, which is unlikely.
You are correct that Series A rounds are usually not smaller, in which case if you raise several million seed on uncapped notes and cannot leverage that into a much more valuable company, you'll be unable to raise a Series A.
This is all manageable by the entrepreneur, but it's important to make sure you understand what's happening and where the risks are. It seems a lot of entrepreneurs don't.
If you raise $3M on a note, you're already implicitly valuing your company at $10M - $15M since since each round is meant to take roughly 20% of your company. Investors wouldn't give you $3M unless they thought your company was worth $10M already and you wouldn't take it unless you thought there was a decent chance of bring your company to a 30M valuation by the time the money ran out.
There is no written rule that says "each round is meant to take roughly 20% of your company", and a company is never guaranteed another round. I know several entrepreneurs who have been given term sheets for over 50% of their company. Or no term sheets at all.
There is no "rule" about implied valuation either. Entrepreneurs can raise $3m in notes $100k at a time, usually from investors that are much less price-sensitive than VCs leading a priced round. It's a lot harder to raise a priced Series A at a $10m+ valuation than raising piecemeal notes at the same valuation cap (or uncapped notes, even).
Again, this is all manageable by the entrepreneur, but there are no "rules" like it often appears from the outside.
The median pre-money Series A valuation for all WSGR startups is ~$8.0m [1], which is likely on the higher end.
Also, uncapped notes do not get diluted when raising your Series A, which is additional dilution for the entrepreneur.
For example, let's say you raise $5m uncapped notes with no discount. If you then raise a $3m Series A at a $8m pre-money valuation, you'll end up giving away more than 50% of your company, not counting interest or option pool. At a $15m pre-money valuation, you'll be giving away over 40% of your company.
Entrepreneurs should be equally careful with SAFEs.
[1] http://www.wsgr.com/publications/PDFSearch/EntrepreneursRepo...