At the last UK general election, the number of Conservative seats won was so high that if every single person eligible to vote in Scotland had voted for Labour, the Conservatives would still have won an outright majority.
The SNP run the gamut. Their supporters are mainly united by wanting independence, and logically would stick to the party most likely to do the formal political work of facilitating it. Some long-term members have left over the recent leadership’s stance on various issues, but many others are determined not to cede “their” party to whatever faction's in power for the moment. Policy-wise, the SNP are classified as centre left just like Scottish Labour. (Even the SGP are now "centre left to left"). Alba, according to Ballot Box Scotland, is unclassifiable ... but they also equate them to the older leftist SNP splinter party Solidarity, which formally joined with Alba, and which Ballot Box considers "left". So, Schroedinger's politicians, I guess.
Alba have also only been around for two years; they weren't founded by Salmond but they got no press coverage at all until he stepped in as leader. The Independence for Scotland Party (ISP), Scotia Future, and Volt - all formed the previous year - got no coverage even locally. All for Unity, their anti-nat counterpart, got probably more than its share because George Galloway's a known name.
Thus, Alba: covered by the press because of Salmond - much more seriously in the European and other segments of the international press than by the UK press, which basically just asked how it felt not to be convicted of sexual assault. But Scotland, like the whole UK, is still heavily conservative in terms of political culture, in spite of bits of PR. I can't see any new party raking in members and seats like in Spain, Italy, France, Poland, Slovakia, Latvia, etc. 2 MPs and a handful of council seats isn't so bad, but Holyrood's essentially had the same five parties since its inception, and the few MSPs who've switched party or gone independent never seem to get re-elected.
Anyway, this GRR position is consistent with Alba's overt support for protecting women's rights (which MRAs are determined to cast as right-wing - women are overprivileged! women aren't even a minority! although I think that script's no longer working as well in Scotland). But most of all, it's part of their overarching "independence first" focus - they've also just launched a petition demanding that ScotGov focus on independence (fair enough, as Sturgeon did promise a second referendum this year) and mentioning a bunch of things including self-ID that they claim have displaced that goal for the SNP.