Yes it's a stupid idea to invest from the beginning during slowstart, why do you need to invest immediately? That's not a problem.
SP says a lot of things, I'll believe these things when I see it. It's just as easy to say I'm going to be making a coin and it'll be released in the next decade, fair for everyone, amazing technological innovations, and large whale investor support! It's like the tagline for every trash coin released in the last three years.
Some people has to invest otherwise barely anyone would mine it. But I see what you mean. Unfortunately ZEC was way overhyped and likely heavily manipulated as well.
And the slowstart was so slow that ZEC was essentially instamined in a sense. Not amount wise, of course, that amount is nothing now but the first couple of people made a lot of money even with a fraction of a coin. Miners were virtually ripping pool owners' throats for payment delays. And then there's early private miners which also hurt distribution.
Anyway, my point is that you don't need ~34 days of climbing to avoid instamining, that's ridiculous. Even if there's a new algo waiting with no public miners.
But this day and age newly a released big coin without a windows wallet and some basic GPU miners for both teams is kind of laughable imo and makes it hard to take it seriously. Even Eth got a lot of flack for it and rightfully so.
A coin with linux/mac/windows wallets and basic GPU (not just CPU) miners at launch and some proper marketing way beforehand shouldn't need more than a few days of slow start.
And if you don't have all that, what's even the point of releasing a half-cooked coin - even if it has a killer feature (other than the obvious answer of making money)? It's not like you want as many people as possible to use it... oh wait.