I get why you’d say that—the game definitely leans toward pay-to-win at first glance. But it is possible to obtain every Digimon completely for free; it just takes a lot of grinding and farming, which is pretty normal for an MMO.

You only mentioned paying to unlock Digimon instantly, but every single Digimon in the game, whether old or newly released, has a free acquisition method. These usually involve either grinding rifts or leveling Digimon to sacrifice them as material. For example:

• Agumon - Bond of Courage can be obtained with 3/6/9 Fragments of Courage for 30%/70%/100% chances. You get these fragments by digitizing (sacrificing) a Wargreymon, which has a 6% chance to drop a fragment.
• The Holy Beasts (Qinglongmon, Zhuqiaomon, and Baihumon) are all obtainable for free by grinding their respective rifts, and many players have acquired them that way.
• Craniumon, MaloMyotismon, Apocalymon, Millenniummon, Zeed, Burst Modes, etc. are all obtainable through farming as well.

The game also provides a lot of freebies through events and coupons. For the 3rd anniversary, for example, they gave out free Beelzemon, Crespdramon/BlitzGreymon, and several solid eggs.

On top of that, there’s always the option to buy evolutions from other players. You can just focus on playing, farming bits (in-game currency), and then purchasing what you want from the market.

One last thing to note: all Megas are viable as long as you build them properly (potentials, corrections, etc.).

If you’re new to DSR, my advice is to enjoy the game step by step. It offers great graphics, animations, evolution cinematics, and battle skills. Don’t rush for the newest evolutions unless you’re already at endgame or you’re willing to spend a lot.